Force feedback control system for video endoscope

ABSTRACT

A video endoscope system includes a reusable control cabinet and an endoscope that is connectable thereto. The endoscope may be used with a single patient and then disposed. The endoscope includes an illumination mechanism, an image sensor, and an elongate shaft having one or more lumens located therein. An articulation joint at the distal end of the endoscope allows the distal end to be oriented by the actuators in the control cabinet or actuators in a control handle of the endoscope. Fluidics, electrical, navigation, image, display and data entry controls are integrated into the system along with other accessories.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 10/811,781, filed Mar. 29, 2004, which is acontinuation-in-part of U.S. patent application Ser. No. 10/406,149,filed Apr. 1, 2003, the benefits of which are claimed under 35 U.S.C. §120 and are herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to medical devices in general andtherapeutic and diagnostic endoscopes in particular.

BACKGROUND OF THE INVENTION

It has become well established that there are major public healthbenefits from regular endoscopic examinations as an aid to the earlydetection and treatment of disease of internal structures such as thealimentary and excretory canals and airways, e.g., the colon, esophagus,stomach, urethra, bladder, ureter, kidney, lungs, bronchi, uterus andother organ systems. A conventional imaging endoscope used for suchprocedures comprises a flexible tube with a fiber optic light guide thatdirects illuminating light from an external light source to the distaltip where it illuminates the region (i.e., tissue, occlusive objects) tobe examined. Frequently, additional optical components are incorporatedto adjust the spread of the light exiting the fiber bundle and thedistal tip. An objective lens and fiber optic imaging light guidecommunicating with a camera at the proximal end of the endoscope, or animaging camera chip at the distal tip, produce an image that isdisplayed to the operator. In addition, most endoscopes include one ormore working channels through which medical devices such as biopsyforceps, snares, fulguration probes, and other tools may be passed.

Navigation of the endoscope through complex and tortuous paths iscritical to success of the examination with minimum pain, side effects,risk, or sedation to the patient. To this end, modern endoscopes includemeans for deflecting the distal tip of the endoscope to follow thepathway of the structure under examination, with minimum deflection orfriction force upon the surrounding tissue, and to survey targetedexamination sites. Control cables similar to bicycle brake cables arecarried within the endoscope body in order to connect a flexible portionof the distal end to a set of control knobs at the proximal endoscopehandle. By manipulating the control knobs, the operator is able to steerthe endoscope during insertion and direct it to a region of interest, inspite of the limitations of such traditional control systems, which maybe bulky, somewhat non-intuitive, and friction-limited. Common operatorcomplaints about traditional endoscopes include their limitedflexibility, limited column strength, and limited operator control ofstiffness along the endoscope length.

For example, conventional, flexible endoscopes are expensive medicaldevices costing in the range of $25,000, and much more with theassociated operator console. The endoscope is expensive because itincludes expensive piece parts and requires laborious hand assembly.Because of the expense, these endoscopes are built to withstand repeateddisinfections and use upon many patients. Conventional endoscopes aregenerally built of strong composite structures typically containingmetals and plastics that do not degrade under reprocessing. Thesematerial structures decrease the flexibility of the endoscope and cancompromise patient comfort. Furthermore, conventional endoscopes arecomplex and fragile instruments that frequently need expensive repair asa result of damage during use or during a disinfection procedure.

To overcome these and other problems, the development of a low costendoscope would allow endoscopes to be used for a single procedure andthen disposed, eliminating the need for preparation and cleaning andincreasing the total volume of endoscopes required. This larger volumewould enable the manufacturer to achieve economies of scale and toincorporate manufacturing methods that are not economical when used incurrent volumes and are only economical in large volumes (100,000units/per year). The low cost endoscope should be packaged sterile ordisinfected and be capable of being used for a single procedure withoutendoscope preparation and then discarded. The endoscope should includeone or more of the following features: better navigation and tracking, asuperior interface with the operator, improved access by reducedfrictional forces upon the lumenal tissue, increased patient comfort,greater clinical productivity and patient throughput than is currentlyavailable with a conventional endoscope, a lower risk ofcross-contamination and the ability to be used across more procedures.

SUMMARY OF THE INVENTION

To address these and other problems in the prior art, the presentinvention is a video endoscope system. In one aspect, the systemincludes a control cabinet, a number of manual or electronic actuatorsthat control the orientation of an endoscope and an imaging system toproduce images collected by an image sensor at the distal end of theendoscope. The endoscope is connectable with the control cabinet andused to examine and/or treat a patient. After the examination procedure,the endoscope is disconnected from the control cabinet and may bedisposed saving the cost and labor of cleaning and resterilizationinherent in traditional reusable endoscopes.

The endoscope of the present invention includes a flexible elongate tubeor shaft and an illumination source that directs light onto anexamination site. An image sensor and objective lens assembly at oradjacent the distal end of the endoscope captures reflected light toproduce an image of the illuminated scene. Images produced by the sensorare transmitted to a display device to be viewed by an operator. In oneembodiment, an imaging assembly at the distal end of the endoscopeincludes an inexpensive mass-produceable assembly of components thathouse one or more light emitting diodes (LEDs), an image sensor such asa CMOS solid state image sensor and low cost (e.g., plastic) lensassembly. The LEDs may be thermally coupled to a heat exchanger, and airor liquid cooled in order to remove any excess heat generated by theLEDs.

The endoscope of the present invention also includes a steeringmechanism such as a number of tensile control cables, which allow thedistal end of the endoscope to be deflected in a desired direction. Inone embodiment of the invention, the proximal end of the tensile controlcables is connected to a mechanical control mechanism (e.g.,knobs)—mounted in a proximal control handle. In another embodiment, thecables communicate with actuators within the control cabinet. In thelatter, a directional controller generates electrical control signalswhich are sent via a processor within the control cabinet, whichgenerates control signals to drive the actuators in order to orient thedistal end of the endoscope in the direction desired by the operator. Inanother embodiment of the invention, the distal end of the endoscope isautomatically steered, based on analysis of images from the imagesensor. A joystick or other directional controller may include tactile,haptic or other sensory feedback to reflect the force against a tissuewall or to alert the operator that the endoscope may be looped. Thedistal tip housing provides a high degree of integration of parts—forexample, clear windows for the LEDs are insert-molded into the distaltip housing to eliminate any secondary window sealing operations and toensure a hermetic seal.

In one embodiment of the invention, the endoscope includes anarticulation joint that is comprised of a number of low cost (e.g.,machine formed, stamped or molded parts), easily mass producedcomponents that allow the distal end of the endoscope to be bent in adesired direction by the control cables. In one embodiment of theinvention, the articulation joint exerts a restoring force such thatupon release of a tensioning force, the distal end of the endoscope willstraighten.

In another embodiment of the invention, the endoscope has a variation instiffness along its length that allows the distal end to be relativelyflexible while the more proximal regions of the endoscope have increasedcolumn strength and torque fidelity so that an operator can navigate theendoscope with greater ease and accuracy and precision through tortuous,compliant anatomy with fewer false advances (“loops”). A presetvariation in mechanical properties (e.g., column strength, bendingmodulus or strength, torsion) along the length can be provided, forexample, by varying the durometer rating or types or dimensions ofmaterials that comprise a shaft of the endoscope. Operator-controlledvariable stiffness can be provided by control cables that can betightened, loosened or torqued to adjust the stiffness of the shaft. Inyet another embodiment, the spacing between the components that comprisethe articulation joint is selected to provide a preset variation instiffness along the length of the articulation joint.

In yet another embodiment of the invention, the endoscope is coveredwith a retractable sleeve that uncovers the distal end of the endoscopeduring use and extends over the distal end after the endoscope isremoved from a patient.

In another embodiment of the invention, the endoscope surface includes amaterial such as a hydrophilic coating, to reduce the coefficient offriction of the endoscope. Other coatings may be used to, for example,improve the device performance, provide an indication of prior use orcontamination or deliver therapeutic agents.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same become betterunderstood by reference to the following detailed description, whentaken in conjunction with the accompanying drawings, wherein:

FIGS. 1A and 1B are schematic illustrations of a video endoscope systemin accordance with exemplary embodiments of the present invention;

FIGS. 1C and 1D illustrate a more detailed view of an embodiment of thevideo endoscope of the present invention;

FIG. 2 illustrates further detail of an endoscope used in the videoendoscope system shown in FIG. 1A;

FIG. 3A is a block diagram of a control cabinet that interfaces with anendoscope in accordance with an embodiment of the present invention;

FIG. 3B is a block diagram of a control cabinet that interfaces with anendoscope in accordance with another embodiment of the presentinvention;

FIG. 3C is a block diagram of a control cabinet and an endoscope inaccordance with another embodiment of the present invention;

FIG. 3D is a more detailed block diagram of the components within acontrol cabinet and their interface to an endoscope in accordance withanother embodiment of the present invention;

FIG. 3E illustrates the communication of data and control signalsbetween a camera control card in the control cabinet and a remote imagesensor at the distal tip of the endoscope in accordance with anotherembodiment of the present invention;

FIG. 3F is a fluidics diagram of a video endoscope shown in FIG. 3C;

FIGS. 3G and 3H illustrate flexible manifolds for use in an embodimentof an endoscope of the present invention;

FIG. 4A illustrates an embodiment of a connector on a control cabinetfor connecting to an endoscope;

FIGS. 4B-4D illustrate an embodiment of a connector for connecting theproximal end of an endoscope to a control cabinet;

FIG. 4E illustrates another embodiment of a control cabinet with aconnector for connecting to an endoscope;

FIG. 4F illustrates a surface of a proximal connector that engages acontrol cabinet in accordance with an embodiment of the presentinvention;

FIG. 4G illustrates an interior of a proximal connector in accordancewith one embodiment of the invention;

FIG. 5A is a detailed view of one embodiment of a handheld controllerfor use with a video endoscope of the present invention;

FIG. 5B illustrates an embodiment of a joystick style controllerincluding a force feedback mechanism for use with an endoscope of thepresent invention;

FIG. 5C illustrates one embodiment of a mechanism for providing forcefeedback to a joystick of the type shown in FIG. 5B;

FIGS. 5D and 5E illustrate another embodiment of a breakout box andhandheld controller of the present invention;

FIGS. 5F-5I illustrate one embodiment of a manual handle for use with anendoscope of the present invention;

FIG. 6A illustrates an embodiment of a distal tip of an endoscope inaccordance with the present invention;

FIGS. 6B-6I illustrate an embodiment of an imaging assembly for use withan endoscope of the present invention;

FIG. 6J illustrates a lens assembly for use with an embodiment of thepresent invention;

FIG. 7 illustrates one mechanism for terminating a number of controlcables in a distal tip of an endoscope in accordance with an embodimentof the present invention;

FIG. 8 illustrates an endoscope having control cables that are routedthrough lumens in the walls of an endoscope shaft in accordance with anembodiment of the present invention;

FIGS. 9A and 9B illustrate a transition guide that routes control cablesfrom a central lumen of an endoscope shaft to control cable lumens in anarticulation joint in accordance with an embodiment of the presentinvention;

FIGS. 10A and 10B illustrate the construction of a shaft portion of anendoscope in accordance with an embodiment of the present invention;

FIG. 11 illustrates one mechanism for providing a shaft with a varyingstiffness along its length in accordance with an embodiment of thepresent invention;

FIGS. 12A and 12B illustrate an extrusion used to make an articulationjoint in accordance with an embodiment of the present invention;

FIG. 13 illustrates an articulation joint in accordance with anembodiment of the present invention;

FIGS. 14 and 15 illustrate an extrusion having areas of a differentdurometer that is used to form an articulation joint in accordance withanother embodiment of the present invention;

FIGS. 16A and 16B illustrate another embodiment of an articulation jointaccording to an embodiment of the invention including a number of balland socket sections;

FIGS. 17A-17D illustrate various possible configurations of ball andsocket sections used to construct an articulation joint;

FIGS. 18A-18B illustrate an articulation joint formed of a number ofstacked discs in accordance with another embodiment of the presentinvention;

FIGS. 19A-19B illustrate a disc used to form an articulation joint inaccordance with another embodiment of the present invention;

FIGS. 20A-20B illustrate a disc used to form an articulation joint inaccordance with another embodiment of the present invention;

FIGS. 21A-21B illustrate a non-circular segment used to form anarticulation joint in accordance with another embodiment of the presentinvention;

FIG. 22 illustrates an endoscope having a braided member as anarticulation joint in accordance with another embodiment of the presentinvention;

FIG. 23 illustrates one possible technique for securing the ends of acontrol wire to a braided articulation joint shown in FIG. 22;

FIGS. 23A-23X illustrate additional embodiments of an articulation jointfor use in an endoscope of the present invention;

FIG. 24 illustrates an endoscope shaft having one or more memoryreducing wraps in accordance with another embodiment of the presentinvention;

FIG. 25 illustrates an endoscope shaft including longitudinal stripes ofa high durometer material in accordance with another embodiment of thepresent invention;

FIGS. 26-29 illustrate alternative embodiments of a gripping mechanismthat rotates an endoscope in accordance with the present invention;

FIGS. 30A and 30B illustrate a retractable sleeve that selectivelycovers an endoscope in accordance with another embodiment of the presentinvention;

FIG. 31 illustrates an embodiment of a passive heat dissipating distaltip of an endoscope in accordance with the present invention; and

FIGS. 32 and 33 illustrate alternative embodiments of a passive heatdissipating distal tip in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As indicated above, the present invention is a video endoscope systemthat allows an operator to access, and view internal body anatomy of apatient as well as to insert surgical instruments into the patient'sbody. In addition, the endoscope may include integrated diagnostic andtherapeutic capabilities to allow the operator to treat the patient in asingle procedure. An endoscope of the present invention can besufficiently inexpensive to manufacture such that the endoscope can beconsidered a single use, disposable item.

As shown in FIG. 1A, a video endoscope system 10 according to oneembodiment of the present invention includes an endoscope 20, a controlcabinet 50 and a handheld controller 80. The endoscope 20 has a distaltip 22 that is advanced into a patient's body cavity and a proximal end24 that is connected to the control cabinet 50. As will be explained infurther detail below, the control cabinet 50 includes a number ofactuators that control a steering mechanism within the endoscope 20 inorder to change the orientation of the distal tip 22. A physician orassistant uses the handheld controller 80 to input control signals thatmove the distal tip 22 of the endoscope 20. In addition, the controlcabinet 50 may include connections to sources of air/gas and a flushingliquid such as water for clearing the endoscope 20, drugs or contrastagents. The control cabinet may also include a network connection (notshown) for allowing the control cabinet to communicate with othercontrol cabinets, computers or the Internet. One or more externalmonitors, PDAs, printers, video recording systems, storage devices andstorage area networks, servers, and hospital information networks orother medical devices can be connected to the control cabinet ifdesired. The control cabinet 50 also includes imaging electronics toprocess and/or transfer signals received from an image sensor, signalscontrolling the image sensor, and patient data to a video display (notshown) for viewing by a physician or technician.

In the embodiment shown, the endoscope 20 also includes a breakout box26 that is positioned approximately midway along the length of theendoscope. The breakout box 26 provides an entrance to a working channeland may include an attachment point for a vacuum collection bottle 40that collects liquids, debris or specimens received from a lumen withinthe endoscope. The vacuum collection bottle 40 is controlled by a vacuumvalve (not shown) that is positioned on the breakout box 26.Alternatively, the valve can be positioned within or connected to thecontrol cabinet 50 and controlled from the handheld controller 80 (see,e.g., FIG. 3D).

If desired, the handheld controller 80 can be secured to or incorporatedinto the breakout box 26 such that the two units can be moved as one.Upon completion of a patient examination procedure, the endoscope 20 isdisconnected from the control cabinet 50 and disposed of. A newendoscope 20 is then connected to the control cabinet 50 for the nextexamination procedure to be performed.

The embodiment shown in FIG. 1A is a “parallel” configuration wherebythe endoscope 20 and handheld controller 80 are separately plugged intodifferent connectors of the control cabinet 50. This parallelconfiguration allows one operator to handle the endoscope while anotheroperator can manipulate the handheld controller 80. Alternatively, thehandheld controller 80 may be secured to the endoscope 20 such that asingle operator can control both. FIG. 1B illustrates a “serial”configuration of the invention. Here, the endoscope 20 is connected tothe control cabinet 50 through the handheld controller 80. In oneembodiment, the handheld controller includes one or more manually drivenactuators that pull or release control cables within the endoscope thatare connected to the distal tip in a manner similar to those found inconventional endoscopes. By tensioning the control cables, the operatoris able to selectively orient the tip of the endoscope. In addition, thehandle contains one or more switches that activate electronics in thecontrol cabinet for the delivery of air or liquid to the endoscope aswell as to control the imaging functions. In yet another embodiment, thehandle may include an operator control that causes actuators in thecontrol cabinet to drive the control cables.

FIGS. 1C and 1D illustrate further detail of an embodiment of the videoendoscope system of the present invention. The control cabinet ismounted on lockable wheels to be easily moved from place to place. Inaddition, the control cabinet supports a video monitor for displayingimages of an examination area and other patient data. A keyboard, ortouch sensor, or multi-positional switch allows the operator to enterdata into a patient file and/or records of the procedure. An endoscope20 is removably secured to the control cabinet 50. In the embodimentshown, the handheld controller is part of the endoscope and includesmanual actuators to move the distal tip as well as switches to activatevarious functions of the system.

FIG. 2 shows further detail of one embodiment of the endoscope 20. Atthe proximal end of the endoscope is a shaft 24, which has a lowertorsional stiffness and a connector 34 that connects the endoscope 20 tothe control cabinet (not shown). Distal to the breakout box 26, theshaft has a higher torsional stiffness. At the distal end of theendoscope 20 is the distal tip 22 that includes a light illuminationport, an image sensor, an opening to a working channel 32 and a flushingport (not shown). Proximal to the distal tip 22 is an articulation joint30 that provides sufficient flexibility to the distal section of theshaft such that the distal tip 22 can be directed over the requireddeflection range (180° or more) by the steering mechanism and can bedirected to bend in any direction desired about the circumference of thedistal tip. That is, the operator can select both the amount of bend orarticulation and the direction of the bend.

As discussed above, the endoscope 20 in accordance with one embodimentof the invention, has a higher torque shaft at the distal section of theendoscope and a lower torque shaft at its proximal end. The breakout box26 positioned along the length of the endoscope shaft can be used as ahandle or gripper to impart rotation of the distal end of the endoscopeduring a medical examination procedure. The higher torque portion of theshaft transfers rotational motion that is imparted at a location nearthe distal tip in order to guide the distal tip of the endoscope. Thelower torque shaft portion of the endoscope intentionally does nottransfer torque as well for ease of manipulation and can twist whenrotational motion is applied and may include one or more rotatablecouplers to aid such rotation.

In use, the operator can insert a medical device such as a biopsyforceps, snare, etc., into an entrance to the working channel 32 of theendoscope found on the breakout box 26. In alternate embodiments, themedical devices may be integrally formed into the endoscope or secured,for example, on the outside thereof. In other alternative embodiments,the entrance to the working channel lumen may be positioned furthertowards the proximal end of the endoscope or the endoscope may includemore than one working channel having entrances located at differentpositions along the endoscope.

FIG. 3A is a block diagram of the major components included within oneembodiment of the control cabinet 50. As indicated above and shown inFIGS. 1C and 1D, the control cabinet 50 is preferably mounted onlockable wheels so that it can easily be placed near a patient prior toan examination procedure. The control cabinet is connected to a sourceof electrical power, either a.c. mains or a battery, as well as to asource of insufflation gas and irrigation liquid. Inside the controlcabinet 50 is a controller interface 52 that is connected to thehandheld controller 80 and receives control signals therefrom. To changethe orientation of the distal tip of the endoscope, the control signalsare received from a directional switch in the handheld controller 80.The control signals are supplied to a servo motor controller 54 that inturn controls a number of actuators, such as servo motors 56 a, 56 b, 56c, 56 d. Each of the servo motors 56 a-56 d is connected to one or morecontrol cables within the endoscope. Motion of the servo motors 56 a-56d pulls or releases the control cables in order to change theorientation of the distal tip 22 of the endoscope 20. Although theembodiment shown in FIG. 3A shows four servo motors and control cables,it will be appreciated that fewer or more servo motors and correspondingcontrol cables could be used to move the distal tip. For example, someendoscopes may use three control cables and three associated servomotors or two motors with four control cables. Similarly, a manualhandle may be equipped with a control knob or other mechanism to tensiontwo or more control cables in order to orient the tip of the endoscope.

An imaging electronics subsystem 60 receives signals transmitted fromthe distal tip through the proximal connector 34 (not shown) and itsassociated electronics at the distal end of the endoscope. In oneembodiment, the image data is brought up from the distal tip in a serialcommunication link, and the signal is reconstituted to produce aformatted image, in this case a 640×480 pixel image. Thisdeserialization reconstructs the image into an array of 10 bit deeppixels—however, other bit depths could be used. The reconstructed imageis an array of pixels corresponding to individual pixels at the imager.Each pixel at the imager is typically filtered by an R, G or B (red,green, blue) filter. Other filtering schemes such as subtractive colorfilters or the well-known Bayer pattern are also possible. Oncereconstituted, the full color image is demosaiced using well knowndemosaicing techniques yielding a full 640×480×30 bit deep RGB colorimage. This image can then be converted to other video standard formatssuch at Y-Cb-Cr-422, NTSC, PAL, S-video, etc.

The imaging electronics subsystem 60 can enhance the images received orcan provide video effects such as zoom, color changes, the incorporationof overlays, color balancing, gamma adjustment, highlighting, etc., orthe addition of functionality such as a graphical user interface priorto display of the images on a video display (not shown). Images of thetissue may also be analyzed by the imaging electronics subsystem 60and/or a separate processing circuit to produce control signals that aresupplied to the servo motor controller 54 in order to automaticallysteer the distal tip of the endoscope as will be discussed in furtherdetail below. Images produced by the imaging electronics subsystem 60may also be printed on a digital printer, sent to a network server orstore, saved to a computer readable media such as a floppy disc, CD,DVD, etc., or a video tape for later retrieval and analysis by aphysician.

The imaging electronics subsystem 60 also provides electrical power to alight source such as a number of light emitting diodes (LEDs) at thedistal end 22 of the imaging endoscope. The gain of the imager or theintensity of the LEDs can be altered to provide for proper exposure ontothe imager. One manner of achieving appropriate exposure is to monitorthe number of saturated pixels and adjust the light source intensity sothat the number of saturated pixels is below a minimum threshold.Another approach is to adjust the light source so that the average pixeloutput is a set percentage, perhaps 50%. Still another is to use AGCalgorithms that are common to the TV or video industry. Proper exposurecan also be obtained either independently or in conjunction withadjusting the light source by changing the gains and/or the integrationperiod of the imager itself. If desired, control signals from theimaging electronics subsystem 60 can adjust parameters of the imager toadjust its overall gain, color balance, and sensitivity.

The LED light source is easily modulatable allowing one to effect theexposure control by adjusting the current to the LEDs and hence theirlight output. Since the output of the LEDs can be readily controlled,one is also able to flicker the light source, by modulating the currentto the LEDs, so as to increase its visibility. This effect, which iswell known in the field of visual perception and to common experience,allows one to determine the location of the distal tip inside the bodyby observing the light that passes through the body to the outsideworld. This is called transillumination. By substantially modulating theoutput of the LEDs at a frequency of 8-14 Hz, the visibility of the tipis maintained using less power or greatly enhanced using the same power.Alternatively, the LEDs can be replaced with small incandescent bulbs orsolid state devices such as a laser.

By pulsing the illumination sources, it is possible to visually detectthe location of the distal tip of the endoscope without fluoroscopy orother external imaging means. If the image sensor is operating when thelight source is pulsed, then the corresponding video display may flickerand distract the operator or impede the ability to see the distal tip.Therefore, during transillumination, it is desirable to prevent flickeron the video display by displaying a static image or disabling the imagesensor or image processor in order to increase the visibility of thedistal tip. If the endoscope utilizes an external light source, then thecontrol cabinet can include a high intensity light source such as alaser or halogen lamp source that supplies light to a fiber opticillumination guide within the imaging endoscope 20 in order toilluminate an internal body organ or desired viewing area. Either powersource 58 may be controlled by signals received from the handheldcontroller 80 when the user desires to activate the light source oradjust the intensity of light produced.

Finally, the control cabinet 50 includes valves 70 that control thedelivery of insufflation air/gas to insufflate a patient's body cavityand an irrigation liquid to flush out a body cavity and/or clean one ormore of the components of the optical assembly (such as the lens orcover window) at the distal end of the endoscope. The insufflationair/gas and irrigation liquid are connected to the endoscope via aconnector 38 that connects to an irrigation/insufflation lumen of theendoscope 20. In one embodiment of the invention, the irrigation andinsufflation functions are provided by the same lumen. However, it willbe appreciated that separate irrigation and insufflation lumens could beprovided if desired and if space in the endoscope permits. Furthermore,additional lumens or the irrigation and insufflation lumens may be usedto deliver therapeutic or contrast substances to the patient.

FIG. 3B illustrates another embodiment of a control cabinet 50A that issimilar to the cabinet shown in FIG. 3A. The control cabinet 50Aincludes a vacuum valve 71 that controls vacuum delivered to a vacuumcollection bottle 40. A vacuum line 73 connects to a vacuum lumen withinthe imaging endoscope 20. The vacuum valve 71 is controlled from thehandheld controller 80. Valving and control of the valves for liquiddelivery and vacuum can be together or separate and can be locatedinside or outside of the cabinet or along the endoscope etc.

FIG. 3C illustrates another embodiment of an endoscope system inaccordance with the present invention. The endoscope system 100 includesa control cabinet 102 that operates to control the orientation andfunctions of an endoscope 104. The control cabinet 102 includes acontroller interface 106 that receives commands from an input devicesuch as a joystick, that is used by the operator to control theoperation of the endoscope. Other examples of input devices includevoice control, head mounted controls, touch pads, track balls, membraneswitches, foot switches, etc. Commands from the joystick are supplied toa programmable processor such as a digital signal processor thatcontrols the overall operation of the imaging system and a servo controlunit 108. The processor and servo control unit control the operation ofa pair of servo motors 110, 112 that in turn drive control cables withinthe endoscope 104. The orientation of the distal tip is controlled inresponse to directional signals received from the user input device aswell as feedback signals obtained from sensors that measure the positionand torque of each of the servo motors 110, 112. In some instances theservo motors 110, 112 may be connected to the control cables through amanually or automatically controlled clutch (not shown). The clutchallows the servo motors to be disengaged from the control cables ifdesired.

In one embodiment of the invention, the processor and servo control unit108 implement a position-to-rate control that varies the speed at whichthe distal tip is moved as a function of the position of the directionalswitch on the user input device. However, other control algorithms suchas position-to-position or position-to-force could also be implemented.The servo control can also be used to vary the position of or articulateinstruments that are within the endoscope.

Another function that may be performed by the processor and servocontrol 108 is to generate a graphical indication of the approximatearticulation of the tip that is shown to the user on the video display.The processor receives feedback signals regarding the position of theservo motors from which the length of control cable shortening isdetermined as well as the torque required to move the cables. From thesevalues, an approximation is made of the amount of articulation at thedistal tip of the endoscope. The approximate articulation amount and thedirection of articulation are displayed to the physician along with theimages received from the image sensor, patient data, and/or otheroperating parameters of the video endoscope system.

The processor and servo control unit 108 also implement a variablebraking function that allows the servo motors 110, 112 to be drivenunder automatic or semi-automatic control by the operator moving thedistal tip within the patient's body. The variable braking isaccomplished by having the operator or the processor select a variablebraking force that is between 0 and the maximum torque that can besupplied by the motors. When the physician moves the endoscope, thetorque on the motors is detected to see if it is greater than or equalto a variable braking threshold. If so, the processor and servo controlunit 108 controls one or both of the servo motors 110, 112 such that thetip is moved to a new position so that the torque readings from themotors are less than the variable braking threshold.

In some instances, such as near delicate portions of the patient'sanatomy, the variable braking threshold will be set to a low value sothat little pressure is required to back-drive the motors. In otherinstances, the braking threshold can be set high where it is desired tomaintain the shape of the endoscope for navigation, etc.

In the manual control version, a variable friction brake may also beused. The user can select the brake force required be adjusting theposition of a lever or dial on the manual controller similar toconventional scopes. One embodiment might involve a separate brake foreach axis or alternatively, one brake may be used for both axes.

The control cabinet 102 also includes an imaging subsystem 114 thatproduces images from the signals that are received from the image sensorat the distal end of the endoscope 104. The imaging subsystem 114deserializes the digital video signal from the CMOS image sensor andperforms the necessary algorithms such as demosaicing, gain control andwhite balance to produce a quality color image. The gain control of thesystem is implemented by adjusting the intensity of the illumination(current supplied to the LEDs) and adjusting the gains applied to thesignals by the CMOS imager. The imaging subsystem 114 also includesisolation circuitry to prevent unacceptable radio frequencysusceptibility, emissions and interference, as well as unacceptableleakage currents in the event of an electrical failure in any circuitwithin the control cabinet 102. The imaging subsystem 114 also includescircuitry for transmitting control signals to the image sensor and forreceiving image signals from the image sensor. In one embodiment of theinvention, the imaging subsystem 114 is provided on a standard “PCI”circuit board to allow the use of standard computer hardware andsoftware.

In the embodiment shown in FIG. 3C, the endoscope 104 has a distal shaftportion 120 that is connected to the breakout box 122 with a swivelconnection 124. In addition, the proximal portion 126 of the shaft isconnected to the breakout box 122 with a second swivel connection 128.The swivel connections 124, 128 allow the distal and proximal ends ofthe endoscope to rotate with respect to the breakout box 122 and withouttwisting the breakout box 122 in the hands of the operator.

In the embodiment shown, the endoscope 104 is connected to the controlcabinet 102 with a connector 130. Within the connector 130 are a pair ofspools 132, 134 that are engageable with the driveshafts of the servomotors 110, 112. Each spool 132, 134 drives a pair of control cables inopposite directions. One pair of control cables drives the distal tip ofthe endoscope in the up and down direction, while the other pair ofcontrol cables drives the distal tip of the endoscope in the left andright direction. Alternatively, a single control cable can be wrappedaround a spool such that a single wire controls movement in a plane.

The connector 130 also includes a manifold 140 that controls the supplyof fluid, air and vacuum to various tubes or lumens within the endoscope104. In addition, the connector 130 includes an electrical connector 142that mates with the corresponding electrical connector on the controlcabinet 102. The connector 142 transfers signals to and from the imagesensor and a thermal sensor as well as power to the illumination LEDs.Water is supplied to the endoscope with a pump 145. The pump 145 ispreferably a peristaltic or isolated chamber pump that moves waterthough a flexible tube that extends into the proximal connector 130.Peristaltic pumps are preferred because the pump driving components donot need to come into contact with the water or other fluids within theendoscope, thus allowing the wetted component to be single use. A waterreservoir 150 connected to the pump 145 or fixedly secured to theproximal connector supplies water to cool the illumination LEDs as wellas to irrigate the region of examination. The water supplied to cool theLEDs is returned to the reservoir 150 in a closed loop. Waste water orother debris are removed from the patient with a vacuum line thatempties into a collection bottle 160. Control of the vacuum to thecollection bottle 160 is provided by a pinch valve within the proximalconnector 130.

FIG. 3D shows further detail of a control cabinet for use with anembodiment of a video endoscope system of the present invention. Withinthe control cabinet 102 is a motherboard 108 that is connected by a PCIdata bus to an articulation and fluids card 109, a camera card 111 andan imaging processing card 114. The image processing card 114 has itsown hard drive connected by a EIDE connection. In addition, the motherboard 108 has its own hard drive and data storage unit such as a DVDwriter that are connected by an EIDE connection or similar interface.The articulation and fluidics card 109 provides signals to a power motordrive that in turn drives the servomotors 110, 112, and receives signalsfrom the shaft encoders and torque sensors to provided feedbackregarding the amount of force required to move the distal tip of theendoscope. The pumps and valves 145 are also controlled by thearticulation and fluidics card 109 to supply insufflation air/gas andirrigation fluids, as well as vacuum, to the endoscope 104 via theproximal connector 130.

Images of the examination area produced by the image sensor within theendoscope 104 are displayed on a digital monitor. The digital monitor isdriven through a multiplexer so that additional data such as patientname, address, date, other physiological parameters, heart rate, bloodpressure, etc., or previously obtained images can be multiplexed ontothe display for view by the operator. In addition, an external digitalmonitor may be coupled to the system, if desired.

The motherboard 108 also interfaces with a printer via an ethernet/USBor parallel connection, and a keyboard by a conventional PS/2 or USBconnection. The handheld controller is connected to the articulation andfluidics card 109 via an RS-422 connection. A speaker is also coupled tothe motherboard 108 to provide audible alarms or status signals to theoperator.

The control cabinet 102 is preferably made using a standardoff-the-shelf computing platform that includes a motherboard, harddrive, video card, processor, memory, etc. Each of the control cards(camera card 111, articulation and fluidics card 198, and the imageprocessing card 114) for the system is plugged into the motherboard in aPCI slot. The motherboard also provides the standard PC type connectors:serial ports, parallel port, Ethernet port, USB ports, microphone in,sound out, etc. The two digital monitors such as LCD display panels onthe control cabinet are connected to a video card that resides in themotherboard in an AGP slot. Essentially, the control cabinet includes ageneric computing platform. This allows exam information to be capturedelectronically in a single integrated system. The types of examinformation that may be captured in this integrated system includes:still images, video clips, voice recordings for annotation purposes,voice input for voice recognition, voice input for voice command and GUInavigation, text labels applied to images, drawing annotations onimages, exam report information, patient discharge information, letterto the referring physician, medications given to the patient, patientvital signs, etc. The exam report can typically include entry for dataelements such as the patient demographics, indication for examination,procedure(s) performed, scope(s) used in exam, instruments used in exam,procedure technique, extent of exam, complications, visualization,tolerance, findings, diagnosis, recommendations, procedure codes,diagnosis codes, interventions performed, pathology specimens collected,etc.

Patient vital signs are preferably recorded via an electronic interface.Vital sign monitors currently allow this type of digital informationexchange over serial ports and Ethernet connections. As indicated,information that is typically collected is systolic blood pressure,diastolic blood pressure, mean arterial pressure, pulse from the bloodpressure measurements, heart rate from an EKG, oxygen saturation, andtemperature. In addition, the control cabinet can include means forelectronic transfer and display of the “wavefomm” data that would allowthe display of waveform signals such as the EKG, respiration, and oxygensaturation. This data is typically provided as a calibrated analogvoltage output. An analog to digital converter (not shown) is used todigitize the waveform data for display on the screens.

The system allows the operator to navigate the system in a number ofways, such as keyboard, touch screen, and a multi-position GUInavigation control switch on the endoscope handle. Any of thesenavigation means may be used before or during an exam to allow theoperator (nurse, physician, or technician) to enter exam-relatedinformation into the control cabinet during the exam. If all of thedesired information is not entered during the course of the exam, thesystem allows the operator to complete the exam record at the end of theexam.

The control cabinet may also contain a barcode scanner or radiofrequency identification (RFID) scanner. This would allow theidentification of tools that are inserted into the working channel ofthe endoscope or otherwise used as part of the procedure. This allowstracking of the equipment or tools that were actually used during theexam. It also allows for intelligent prompting for the user through theGUI to record relevant information about the use of the items that werescanned. For example, the nurse scans a biopsy forceps before it isinserted into the working channel of the endoscope. The control cabinetGUI then automatically prompts the user with the typical interventionsperformed with the type of forceps that were inserted. The system wouldalso prompt the user to enter information about the biopsy specimen(s)(location, description, pathology to be evaluated) such that informationis entered in an automated fashion for a pathology requisition. Thesystem could also prompt the user with default operating parameters forthe instruments.

FIG. 3E shows the signals that may be transmitted from the camera card111 to the image sensor and associated devices at the distal tip of theendoscope. The camera card 111 receives isolated power and containsconventional circuitry for a sync and color space conversion, automaticgain control, white balance initialization, pixel correction interlacerand a frame memory. Circuits are provided for low voltage differentialsignaling (LVDS). The camera card 111 contains an amplifier that drivesthe illumination light sources, such as LEDs. The camera card 111provides an LVDS master clock signal to an LVDS clock receiver that iscoupled to the CMOS image sensor at the distal end of the endoscope. Bynot including the master clock at the distal end of the endoscope, thecost of the imaging electronics for each endoscope is further reduced.The camera card 111 receives video and sync signals transmitted at 162Mbps LVDS signaling, which are deserialized and provided to the on-boardprocessor. In addition, the camera card receives thermistor signalsreceived from a thermistor or other temperature sensor at the distal endof the endoscope. The camera card produces NTSC/PAL video signals thatcan be output to displays or other devices. In addition, the boardprovides embedded sync signals and progressive YUV Signals. The cameracard 111 includes its own EPROM for storing firmware that may beupdated, if necessary, and a frame memory for storing video frames.

FIG. 3F is a fluidics diagram of an embodiment of the endoscope 104 asshown in FIGS. 3C and 3D. As indicated above, a water supply 150, suchas a plastic fluid reservoir containing a fluid such as sterilized wateror saline, is used to supply water to the endoscope with a peristalticpump 142. The water is pumped into a tube or lumen 162 that delivers thewater to a heat exchanger coupled to the LED illumination source. Waterreturning from the heat exchanger is received in a tube 164 and passedthrough a flow meter 166 back to the reservoir 150. In this embodimentof the invention, water is continually pumped through the heat exchangerto prevent the illumination sources from becoming too hot. The flowmeter 166 provides a signal if water is not being pumped through theheat exchanger so that the operator may be warned to remove theendoscope from the patient and/or the LEDs may be turned off or theiroutput intensity lowered to prevent a thermal hazard to the patient. Inaddition, the fluid reservoir may include electronic sensors, movablefloats, windows, alarms, etc., to indicate the level of cooling fluidavailable and whether an additional supply of liquid should be provided.A temperature monitor, such as a thermistor, in the distal tip canprovide warning of a potential thermal hazard.

In addition to providing cooling, water can be selectively applied to atube 170 that provides a high pressure lavage for irrigating a patientlumen, as well as a lens wash tube 172 that cleans contaminants from thefront of an imaging lens at the distal end of the endoscope. Water canalso be selectively applied to a tube 174 that is connected to a workingchannel tube of the endoscope to clean the working channel, ifnecessary. The flow of water in each of the tubes 170, 172, 174 isselectively controlled by an associated valve which allows water to bepumped through the tube if desired. A valve 180 controls the applicationof vacuum to a working channel tube in the endoscope to removeirrigation liquid, debris, or other contaminants from the patient, ifdesired. A valve 182 controls the supply of air or other bio-compatiblegas to an insufflation lumen, which in an embodiment of the invention isthe same tube as the lens wash tube 172 at the distal end of theendoscope. The air can be provided to the patient under a variety ofpressures using solenoid valves 184, 186, 188 in line with regulators oran electronically controlled regulator or programmable array ofregulators that provide air at different pressures and are connected inparallel to an air or gas source. The pressure of air delivered to thelens wash tube 172 can be adjusted by selectively opening a combinationof the valves 184, 186, 188. A check or anti-siphon valve 189 is in linewith the air supply line to prevent any back flow of air or liquids fromthe endoscope into the air delivery mechanism.

FIG. 3G shows one embodiment of a manifold 140 that directs air, waterand/or vacuum to the various tubes or lumens within the endoscope. Inone embodiment of the invention, the manifold is formed of two sheets ofa thermoplastic material such as polyurethane that are RF welded orotherwise bonded to form a series of passages or channels between thesheets. Pinch valves or side clamps may be used on the vacuum line toprevent uncontrolled vacuum when connecting or disconnecting theconnector to the control cabinet. Pinch valves are placed over thepassages or channels and are selectively opened or closed to control thedelivery of fluids, air or vacuum to the different tubes in theendoscope. In one embodiment, the manifold 140 has three connectors onone side and six connectors on the other side. On one side, a connector190 receives water from the water reservoir 150. A connector 192 isconnected to a tube that returns the water from the heat exchanger atthe distal tip to the water reservoir 150, and a connector 194 isconnected to a collection jar 160 that is in-line with the vacuumsource. Pinch valves are preferred because the valve actuator componentsdo not need to come into contact with the water or other fluids withinthe endoscope and they allow the wetted component to be single use. Inaddition, pinch valves provide for a simple valveless design.

In the embodiment shown, a connector 196 is connected to the workingchannel to supply water to or apply vacuum to the working channel. Aconnector 198 is connected to the insufflation tube. A connector 200 isconnected to the high pressure lavage tube in the endoscope. Connectors204 and 206 are connected to the tubes that supply water to and returnwater from the heat exchanger that cools the LED illumination sources.

Water entering the manifold at the connector 190 is allowed to flow infour different paths. Fluid flow through three of the paths isselectively controlled with solenoid valves that pinch the manifold 140at locations 208, 210, 212 that are over the passages in the manifold.In one embodiment of the invention, water is always pumped through theheat exchanger that cools the LED illumination sources. By selectivelyactivating the solenoid valves at the locations 208, 210, 212, water canbe supplied to the other tubes in the endoscope.

In addition, the manifold 140 includes a support tube or otherstraw-like structure that maintains the passage open between theconnectors 196 and 194 such that vacuum does not collapse the manifold140 when a solenoid valve that is at a location 214 between theconnectors 194 and 196 is released. The tube or straw also includes atleast one perforation (not shown) to allow liquid to flow into theworking channel if desired.

After use, the manifold 140 is removed from the tubes that supply waterand vacuum, etc., and is disposed of along with the rest of theendoscope. The flexible manifold bag 140 forms an inexpensive device forcontrolling the application of fluids or air to the endoscope whilepreventing the fluids from coming in contact with non-disposableportions of the video endoscope system itself.

FIG. 3H shows another embodiment of a flexible manifold 152. Fluidenters the manifold 152 from the fluid reservoir through an inlet 152 a.Fluid is pumped into tubing and the fluid path is selectively controlledby a series of pinch valves 152 b. Fluid is allowed to flow selectivelythrough a line 152 e for a bolus wash, through a line 152 c for a lenswash and through a line 152 d for a jet wash. Fluid continuously flowsout through a line 152 f to a heat exchanger in the distal tip for LEDcooling. Fluid returns from the heat exchanger through line 152 h fromwhich is flows through a flowmeter (not shown), and returns back to thefluid reservoir through a fluid outlet 152 j.

FIG. 4A illustrates one embodiment of a connector for securing theproximal end of the endoscope to a control cabinet 250 prior toperforming an endoscopic examination. The control cabinet 250 includesan exterior connector 252 having a number of shafts 254 that are coupledto the servo motors of the type shown in FIGS. 3A, 3B, and 3C. Eachshaft 254 is shaped to be received in a corresponding spool on which thecontrol cables are wound. Also included in the connector 252 areconnections to the insufflation and irrigation valves 256 and a vacuumvalve 258 to provide air, water and vacuum to the endoscope.

FIGS. 4B and 4C illustrate one embodiment of a connector 260 used tosecure the proximal end of the endoscope 20 to the control cabinet 250.The connector 260 includes a number of thumbscrews 262, a form-fittedclosure door, or other quick release mechanisms that allow the connector260 to be easily secured to the exterior connector 252 on the exteriorof the control cabinet 250. As shown in FIG. 4C, the connector 260includes a number of spools 262 about which the control cables arewound. Each spool is preferably threaded or grooved to prevent thecontrol cables from binding on the spool during use. A sheave or flange265 may surround a portion of the spool to keep the control cablesagainst the spool and within the groove and to aid in supporting thespool within the connector 260. In one embodiment of the invention, thespools are prevented from rotating and thus the cables from unwindingwhen the connector 260 is not engaged with the control cabinet 250 bybrakes 266 having pins that fit within corresponding slots in thespools. Once the connector 260 is mounted to the control cabinet 250,the brakes 266 are disengaged from the spools such that the spools canbe moved by the servo motors. A clamp 267 can be used to secure theproximal end on an outer jacket that covers the control cables.Electrical connections for the light sources and image sensor as well asconnections to the air and water valves are placed on the sides of theconnector 260 or on the rear face of the connector 260 to engage thevalves, as shown in FIG. 4A.

FIG. 4D illustrates a cross-sectional view of a splined shaft 254 fittedwithin a spool 262 with a splined bore. The shaft 254 is supported by acylinder 256 having a spring 258 therein such that the shaft 254 is freeto move within the cylinder 256. The cylinder 256 is coupled, eitherdirectly or through a clutch, to the servo motors within the controlcabinet. The spring 258 allows the shaft 254 to float such that theshaft can more easily align and engage the mating surface of the spool262 when the connector is attached to the control cabinet 250.

Upon insertion of the shaft 254 into the spool 262, the brake 266 isreleased, thereby allowing the spool 262 to be moved by rotation of thecylinder 256. In some instances, the brake 266 may be omitted, therebyallowing the spools 262 to freely rotate when the connector 260 is notengaged with the control cabinet 250.

FIG. 4E illustrates another embodiment of a control cabinet 280 having adisplay 282 upon which a graphical user interface including patient dataand video or still images produced from the endoscope are presented. Aconnector 284 is provided on the exterior of the control cabinet 280 forconnecting the proximal end of the endoscope. The connector 284 includesa number of shafts 286 that are coupled to the servo motors within thecontrol cabinet. A number of pinch valves 288 are provided to controlthe flow of air, water, and vacuum through the manifold that connectsthe fluid reservoir, vacuum source, and air supply (not shown) to thetubes in the endoscope. A peristaltic pump 290 is provided for pumpingliquid through the endoscope as described above. A joystick handheldcontroller 292 is connected to the control cabinet 280 so that anoperator can enter commands concerning the operation of an endoscope andits orientation.

FIG. 4F shows the rear surface of one embodiment of a proximal connector130 that couples the endoscope to the control cabinet. The proximalconnector may be seated into a movable door on the control cabinet,which is then closed to connect the connector 130 to the controlcabinet. As discussed above, the connector 130 has an electricalconnector therein that mates with a corresponding electrical connectoron the control cabinet to transfer LVDS signals, including an upstreamclock signal to the image sensor, power and grounds to the illuminationLEDs, and regulated power for the image sensor. Electrical signalsreceived back from the endoscope include a thermistor signal, and LVDSformatted, serialized video and sync data. Water inlet port 296 andwater outlet port 298 supply fluids to a manifold within the proximalconnector.

FIG. 4G shows a cross-sectional view of the proximal connector 130 shownin FIG. 4F. As shown, a series of raised knobs with anvils 299A, 299B,299C, 299D are located along one side of the proximal connector 130. Thesharp edges on the anvils 299A-299C function to provide a backing to theflexible manifold bag inside the proximal connector housing and allowthe solenoid valves to pinch the manifold and restrict the flow. Theraised knob and anvil 299D provides a support to the vacuum tube underthe manifold in the proximal connector housing to allow the solenoidvalve to pinch the tube and control the vacuum.

FIG. 5A illustrates various controls located on one embodiment of ahandheld controller 300 in accordance with the present invention. Thehandheld controller 300 includes a controller body 302 that, in aparallel embodiment of the invention, is coupled to a control cabinet byan electrical cord 304, a wireless radio frequency channel, an infraredor other wireless or optical link. If the connection is made with anelectrical cable, a strain relief 86 is positioned at the junction ofthe electrical cable 304 and the body 302 of the controller to allowsuitable flexing and bending of the electrical wires within theelectrical cable 304. In a serial embodiment, the connection of thehandheld controller 300 to a control cabinet is made with a sheath thatincludes both the wires to transmit signals to the motion controllersand imaging system, as well as lumens to carry the insufflation air/gasand irrigation liquid. In addition, the control cables of the endoscopeengage cables that are connected to the actuators in the motion controlcabinet through the handheld controller 300. If used with a manualhandle, the connection to the control cabinet is made with a sheath thatincludes wires to transmit signals to and from the image sensor, theillumination LEDs and lumens to carry the insufflation air/gas andirrigation/cooling liquid.

Positioned in an ergonomic arrangement on the handheld controller 300are a number of electrical switches. An articulation joystick 308 orother multi-positional device can be moved in a number of directions toallow the physician to orient the distal tip of the imaging endoscope ina desired direction. In order to guide the imaging endoscope manually,the physician moves the joystick 308 while watching an image on a videomonitor or by viewing the position of the distal tip with anothermedical imaging technique such as fluoroscopy. As the distal tip of theendoscope is steered by moving the joystick 308 in the desireddirection, the physician can push, pull and/or twist the endoscope toguide the distal tip in the desired direction.

A camera button 310 is provided to capture an image of an internal bodycavity or organ in which the endoscope is placed. The images collectedmay be still images or video clips. The images may be adjusted forcontrast or otherwise enhanced prior to display or stored on arecordable media.

An irrigation button 312 activates an irrigation source to supply aliquid such as water through an irrigation lumen of the endoscope. Theliquid serves to clean a window in front of an image sensor and/or thelight source at the distal end of the endoscope as well as an area ofthe body cavity. An insufflation button 314 is provided to activate theinsufflation source to supply air/gas through a lumen of the endoscope.The supply of the insufflation gas expands portions of the body cavitysurrounding the distal tip of the endoscope so that the physician canmore easily advance the endoscope or better see the tissue in front ofthe endoscope.

In one embodiment of the invention, the body 302 of the handheldcontroller 300 also includes a detachable joint such as a thumb screw316 for securing the handheld controller 300 to the breakout box asindicated above. A corresponding socket or set of threads on a breakoutbox receive the thumb screw 316 in order to join the two parts together.One or more additional buttons 318 may also be provided to activateadditional functions such as recording or printing images, adjustinglight intensity, activating a vacuum control valve or providing avariable braking drag on the control cables that provide the up, down,left, right movement of the distal tip, etc., if desired.

FIG. 5B illustrates another embodiment of a hand held controller bywhich the operator can enter commands to control the operation of thecontrol cabinet and endoscope. The controller 350 includes a handle 352that is ergonomically shaped to allow the user to control the operationswith his or her thumb and/or fingers. A joystick 354 is located on thetop of the controller 350 such that the user can steer the endoscope bymoving the joystick with their thumb. A number of control buttons 356can be activated with the user's thumb or fingers to control otheroperations of the endoscope such as supplying air for insufflation orwater/vacuum to the lumens in the endoscope adjusting the illuminationsource intensity, etc. The controller 350 also includes a force feedbackmechanism 360 that applies a variable force to a spring 362 that biasesthe joystick 354. The force applied by the feedback mechanism 360 isvaried in proportion to the force required to steer the endoscope. Forexample, the endoscope may be positioned against a tissue wall, or mayhave a number of loops along its length. Therefore, the user can begiven a tactile indication of the force required to steer the endoscopeby varying the force placed on the spring 362 by the feedback mechanism360.

As indicated above, in one embodiment of the invention, the servo motorsimplement a position-to-rate control algorithm, whereby the position ofthe joystick 354 is translated into a rate of change of position in adesired direction in the distal tip. Therefore, as the user presses thejoystick in any direction, the return force that is applied by the forcefeedback mechanism 360 to the spring 362 can be varied as a function ofthe drive motor torque required to move the control cable and varyingthe force on the spring also varies the force that the spring applies tothe joystick. The force that the spring applies to the joystick is feltby the user through the joystick and gives the user a tactile indicationof the level of force being applied to move the distal tip in thedirection being commanded by the user.

FIG. 5C illustrates one mechanism for providing a force feedbackmechanism 360 within the handheld controller 350. Within the joystick isa motor 370 that drives a rack and pinion mechanism including a firstrack 372 that is directly coupled to the motor 370 and a second rack 374that is directly coupled to the pretension spring 362. Rotation of themotor 370 drives a screw-type mechanism (not shown) which moves thefirst rack 372 up or down. A pinion gear 376 translates longitudinalmotion of the first rack 372 into longitudinal motion of the second rack374, which in turn adjusts the pretension on the spring 362. In theembodiment shown, two racks are needed due to the orientation of thejoystick with respect to the longitudinal axis of the hand heldcontroller 350. However, other configurations could be used if thejoystick were oriented differently in the hand held controller. Forexample, linear motor drive joysticks could be configured to providerapid force feedback to the user.

Similarly, other structures and/or materials, such as elastomers orflexural structures can be used to replace the spring entirely and aforce can be applied to one area of the plastic material to create asimilar force where the plastic contacts and biases the joystick.Similarly, variable torque motors can be coupled directly to thejoystick and the torque of the motors adjusted in accordance with thetension of the control cables to directly transmit a force through thejoystick to the user. The use of two motors with the motors acting onorthogonal respective axes of the joystick movement can create forcefeedback signals in response to all possible directions of joystickmovement. This sort of use and arrangement of direct drive motors can besimilarly used to feedback position of the distal tip. In thisarrangement, position controlled motors would be used instead of torquecontrolled motors. The positions of the control cables or the positionsof the servo motors driving these cables are used to compute theapproximate position of the distal tip. The position controlled motorsare driven to make the joystick position follow the computed position ofthe distal tip. If the operator attempted to move the tip and the motionof the tip were blocked by its environment, then the operator's movementof the joystick would be resisted by forces applied by the positioncontrolled motors to make the joystick position correspond with the tipposition.

Although the embodiment shown discloses a motor and a rack and piniongear system to change the compression of the spring 362 that biases thejoystick 354, it will be appreciated that other mechanisms includinghydraulic, or magnetic actuators could be used. Alternatively, asdiscussed above, pseudo-fluid devices such as thermoplastics can beused. By selectively compressing a thermoplastic material, itselasticity can change and be used to apply different pressures on aspring 362.

In another embodiment, not all the forces on the wires are fed back to auser. In one embodiment, the system distinguishes the resistance of theshaft versus the resistance at the distal tip and only the resistance atthe distal tip is fed back to a user.

To distinguish the forces on the shaft versus the forces at the tip, thetip is dithered in different directions. If the resistance is on thetip, then the resistance should be high only in one direction. Ifresistance is caused by loops in the shaft, then resistance should beequal in all directions. By comparing the forces in a processor andseparating the forces required to move the distal tip, high forces canbe prevented from building up at the tip. High motor torque can be usedonly to overcome resistance due to looping and not employed to bend thetip if it meets resistance. Therefore, higher forces are prevented frombeing built up on the tip, lowering the risk that the tip will perforatethe anatomy or undesirably snap into position.

FIGS. 5D and 5E illustrate another embodiment of a breakout box andhandheld controller. In this embodiment, a breakout box 380 has a distalend 382 and a proximal end 384. The breakout box is generally“banana-shaped” such that it fits ergometrically in a user's hand. Inaddition, the proximal end 384 of the breakout box 380 is oriented suchthat when the user has the controller in his or her hand and the palm isoriented horizontally with respect to the floor, the proximal end ispointed downwards toward the floor. Therefore, the proximal end of theendoscope shaft extending from the breakout box is angled away from thephysician's forearm and is less likely to get in the way.

The breakout box 380 also includes an entrance to the working channel386 having a cap thereon. The cap is positioned such that the entranceto the working channel does not face the physician in order to lessenthe chances of the physician or nurse being sprayed by bodily fluids orother contaminants. The cap may be removable or integrated into thebreakout box and may include a duck bill or tuey bohrs that enables aphysician to effectively seal around a device to prevent air and fluidleakage. By removing the cap, a user can insert a tool into the workingchannel for receiving biopsies, applying medication, or performing othermedical procedures.

Selectively coupled to the breakout box 380 is a handheld controller388. The handheld controller includes a directional switch 390 thatcontrols the orientation of a distal tip of the endoscope. Furtherbuttons or controls 392 may be provided to allow the user to activateadditional features of the endoscope or change operating parameters ofthe video endoscope system.

Other embodiments may not require the cap to be removed. The cap mayconsist of a duck bill valve which allows passage of the device butimmediately seals itself once the device has been removed. This ensuresthat the user will never get sprayed if the bolus wash is applied whilethe cap is removed. Another design involves a screw cap which tightensdown on the duck bill valve to hold the device steady at a preciselocation.

As shown in FIG. 5D, the handheld controller 388 is selectively coupledto the breakout box 380 by cooperating male and female joiningmechanisms 396, 398. In the embodiment shown, the joining mechanismscomprise a tab which is elastically received in a corresponding slot.However, other attachment mechanisms could be used.

FIGS. 5F-5I illustrate one embodiment of a manual handle includingrotatable knobs that tension the control cables to steer the distal tipof the endoscope. The manual handle includes a number of electronicswitches that direct electronics in the control cabinet to activatevarious functions of the endoscope system, such as suction, air, lenswash, jet wash or low pressure lavage and bolus wash. Additionalswitches are provided to be thumb activated, such as a menu button and amulti-position switch for navigating menus on the display.

In one embodiment of the invention, several simple switches are used tocontrol water, air, suction, lens wash image management, and graphicaluser interface (GUI) navigation. The switches are wired to a circuitboard in the handle or connector with multiple wires. A microprocessorprovides the button signals to the control cabinet on a few wires. Theswitches can be relatively inexpensive because the switches do not needto withstand repeated use or cleaning. In addition, other functions suchas debouncing, etc., that might increase the cost of the switch can beprovided within the control unit by dedicated hardware or software, forexample.

In one embodiment of the invention, the knobs on the handle are coupledto the control wires with a “bead chain” of the type commonly used withlamp pull-switches. The bead chain engages in a sprocket connected tothe knobs. The force required to turn the knobs and the amount ofrotation of the knobs required to articulate the tip can be controlledby adjusting the size of the sprocket. Larger sprockets will requiremore force to turn the knob but will require less rotation and will havehigher force feedback. Smaller sprockets will require less force butmore rotation. It is possible that a different size sprocket be used onthe up/down axis than on the left/right axis. In one embodiment, thesteering cables are connected directly to the bead chain. In otherembodiments, the steering cables can be wrapped directly around thesprocket. In other embodiments (as shown in FIG. 51), the bead chain isconnected to the steering cable using a spring. The stiffness of thespring can be adjusted to maintain uniform tension in steering systemwhen loops are created in the distal shaft during an endoscopicprocedure. In other embodiments, the spring can be put on the end of thetightly wound spring coils which the steering cables run through. Thissprings may also be used to ensure that all disposable devices have thesame feel to the user and prevent slack from building up in the devicesduring storage prior to use. This ensures that all devices will beresponsive to the user and will not have slop.

A fixed stop may be placed on the sprocket, on the bead chain, on thepull cable or on the knobs to limit the rotation of the knob and avoidover articulating the tip.

An entrance to the working channel is positioned below the knobs toallow the insertion of tools into the working channel. The workingchannel port may be fixed to the manual controller housing or may beallow to translate along the main axis of the housing. Allowing theworking channel port to translate, will prevent tensile forces frombuilding up on the working channel when loops are created in the distalshaft.

The manual controller housing will allow space for excess length ofbowden cables, electrical cables and utility tubes. This preventstensile forces from building up on these components when loops arecreated in the distal shaft.

In other embodiments, the handheld controller may be fitted to agripping mechanism that grasps the distal portion of the shaft. Theoperator can therefore secure the handheld controller to the shaft atvarious positions along its length in order to allow the physician to becloser to the patient.

Although the disclosed embodiments of the endoscope generally require anoperator to control the orientation of the distal tip, the endoscope ofthe present invention may also be steered automatically. Images receivedby the imaging electronics are analyzed by a programmed processor todetermine a desired direction or orientation of the distal tip of theendoscope. In the case of a colonoscopy, where the endoscope is advancedto the cecum, the processor controls the delivery of insufflationair/gas to inflate the colon. The processor then analyzes the image ofthe colon for a dark open lumen that generally marks the direction inwhich the endoscope is to be advanced. The processor then suppliescontrol instructions to the servo controller such that the distal tip isoriented in the direction of the dark area so located.

In other modes, a processor in the control cabinet causes the distal tipof the endoscope to move in a predefined pattern. For example, as theendoscope is being withdrawn, the distal tip may be caused to move in aspiral search pattern such that all areas of a body cavity are scannedfor the presence of disease. By using the automatic control of thedistal tip, a physician only has to advance or retract the endoscope toperform an examination and concentrate fully on image interpretation.

As will be described in further detail below, the endoscope generallycomprises a hollow shaft having one or more lumens formed of plasticmaterials, such as polyurethane or polyethylene, which terminate at thedistal tip. The shape of the distal tip and shaft is usually cylindricalbut can be made in other shapes to facilitate passage into a bodycavity. In addition, the tube for the working channel may be supportedwith a spring in the area of the articulation joint to prevent kinking.In addition, the lumens may be reinforced with a spiral wound wrap ofmetal wire or polymer or glass fiber or tape. The lumens can havevarious cross-sectional shapes along the length such as circular, oval,asymmetrical, etc. The outsides surface of the tubes may be lubricatedto help them slide relative to each other during articulation.Alternatively, ‘frosted tubes’ may be used to lower the coefficient offriction on the outside surface. The internal wall of all tubes willusually be smooth. One embodiment of the working channel involves a starshaped lumen rather than a circular lumen. This reduces the contact areawith devices and allows devices pass through with less force. As shownin FIG. 6A, one embodiment of a distal tip 400 comprises a cylinderhaving a distal section 402 and a proximal section 404. The proximalsection 404 has a smaller diameter than the diameter of the distalsection 402 in order to form a stepped shoulder region. The diameter ofthe shoulder is selected such that shaft walls of the endoscope can seaton the shoulder region to form a smooth outer surface with the distalsection 402. The distal face of the distal tip 400 includes a number ofports, including a camera port 406, one or more illumination ports 408,an access port for the working channel lumen 410, and a directionalflush port 412.

Fitted within the camera port 406 is an image sensor (not shown) thatpreferably comprises a CMOS imaging sensor or other solid state imagingdevice and one or more glass or polymeric lenses that produceselectronic signals representative of an image of the scene in front ofthe camera port 406. The image sensor is preferably a low lightsensitive, low noise, CMOS color imager with VGA resolution or highersuch as SVGA, SXGA, XGA, or UXGA, etc. If less resolution is desired, a½ or ¼ VGA sensor could also be used. For conventional video systems, aminimum frame rate of 25 to 30 fps is required to achieve real-timevideo. The video output of the system is desirably transmitted to theconsole in a digital form, but may be in any conventional digital oranalog format, including PAL or NTSC, or high definition video format.

The illumination ports 408 house one or more lenses/windows and one ormore light emitting diodes (LEDs) (not shown). The LEDs may be highintensity white light sources or may comprise light sources at otherwavelengths such as infrared (IR) red, green, blue or ultra-violet (UV)LEDs. With colored LEDs, images in different spectral bands may beobtained by illumination with any one or more individual colors. Whitelight images may be obtained by the simultaneous or sequentialillumination of the colored LEDs and combining individual color imagesat each illumination wavelength. If sequential illumination of coloredLEDs is employed, as an alternative, a monochrome CMOS imager can beused. As an alternative to LEDs, the light source may be external to theendoscope and the illumination light delivered to the illumination portwith a fiber optic bundle and traditional light sources. Alternatives toa LED source at the distal tip could include, for example, anincandescent lamp or lamps, or organic LEDs, photomic crystals, or lasersources.

The access port 410 is the termination point of the working channel orlumen of the endoscope. In one embodiment, the proximal end of theworking channel terminates at the breakout box 26 as shown in FIG. 2.However, the working channel could terminate nearer the proximal end ofthe endoscope.

The directional flush port 412 includes a cap 414 that directs liquidand air supplied through an irrigation and insufflation lumen across thefront face of the distal tip 400 in the direction of the camera port 406and/or the illumination ports 408. The cap 414 thereby serves to rinse,clean and dry the camera port 406 and the illumination port 408 for abetter view of the internal body cavity in which the endoscope isplaced. In addition, the flushing liquid cleans an area of tissuesurrounding the distal end of the endoscope.

FIGS. 6B-6I illustrate another embodiment of an imaging assembly thatforms the distal tip of the disposable endoscope in accordance with thepresent invention. The imaging assembly is low cost, compatible withinexpensive assembly techniques, and performs comparably to moreexpensive imaging mechanisms such that an operator finds the endoscopeoperation familiar for the examination of patients.

As shown in FIG. 6B, the distal end of the endoscope includes a distalcap having a number of openings on its front face. The openings includean opening to a working channel 452 and an opening 454 for a lowpressure lavage, whereby a stream of liquid can be delivered through theendoscope for removing debris or obstructions from the patient. A lenswash and insufflation port includes an integrated flush cap 456 thatdirects water across the lens of an image sensor and delivers aninsufflation gas to expand the lumen in which the endoscope is inserted.Offset from the longitudinal axis of the endoscope is a lens port 458that is surrounded by a pair of windows or lenses 460 and 462 that coverthe illumination sources.

As best shown in FIG. 6C, the imaging assembly includes the distal cap450, a cylindrically shaped lens assembly 470, and a heat exchanger 480.The heat exchanger 480 comprises a semi-circular section having aconcave recess 482 into which the cylindrically shaped lens assembly 470can be fitted. The concave recess 480 holds the position of the lensassembly 470 in directions perpendicular to the longitudinal axis ofendoscope, thereby only permitting the lens assembly 470 to move alongthe longitudinal axis of the endoscope. Once the lens assembly ispositioned such that it is focused on an image sensor 490 that issecured to a rear surface of the heat exchanger 480, the lens assemblyis fixed in the heat exchanger with an adhesive; this may be facilitatedby the application of precise stops or lands in the molded part design.A pair of LEDs 484, 486 are bonded to a circuit board which is affixedin the heat exchanger such that a channel is formed behind the circuitboard for the passage of a fluid or gas to cool the LEDs. A circuitboard or flex circuit 492 containing circuitry to transmit and receivesignals to and from the control unit is secured behind the image sensor490 and to the rear surface of the heat exchanger 480. With the lensassembly 470, the LEDs 484, 486, the image sensor 490, and associatedcircuitry 492 secured in the heat exchanger 480, the heat exchangerassembly can be fitted within the distal cap 450 to complete the imagingassembly as shown in FIG. 6D.

FIG. 6E is a rear isometric view of the distal cap 450. The distal cap450 is preferably precision molded out of ABS or other bio-compatiblematerial. As indicated above, the front face of the distal cap 450includes an integrated flush cap 456 and pair of windows 460 that arepositioned in front of the LEDs. Preferably, the windows are made of aclear plastic material such as polycarbonate, which are overmolded withthe remainder of the distal cap 450. Also within the inside of distalcap 450 is a flat surface 470 that extends proximally, thereby dividingthe cylindrical inner surface of the distal cap into a semicircular tubeinto which the semicircular heat exchanger 480 assembly can be fitted. Aprotrusion 472 extends from the inside front face of the distal cap 450and is aligned with a front face of the heat exchanger 480 to limit theextent to which the heat exchanger 480 can be inserted into the distalcap 450.

FIG. 6F is a cross-sectional view of the windows 460, 462 that arepositioned in front of the LEDs. The windows 460 are preferably moldedof an optically clear plastic material with an outwardly extendingflange 464 that secures the window 460 in front face of the distal cap450. Once the windows have been molded, the distal cap 450 can be moldedover the windows 460, 462 in order to secure them in place.

FIG. 6G is a front isometric view of the heat exchanger 480 portion ofthe imaging assembly. As indicated above, the heat exchanger is asemicircular section having a relatively flat bottom surface 500 thatmates with the flat surface 470 in the inside of distal cap 450 and arounded upper surface 502. The interior of the heat exchanger isgenerally hollow to form a channel through which a cooling liquid or gascan be passed to remove excess heat from the illumination LEDs. Theconcave recess 482 is formed in the bottom flat surface 500 of the heatexchanger to receive the cylindrically shaped lens assembly 470, asshown in FIG. 6C. Extending rearwardly from the heat exchanger 480 are apair of legs 506, 508 having holes therein that are fluidly connected tothe interior of the heat exchanger 480. A lip 512 extends around theinside surface of the front face of the heat exchanger 482 to form abonding surface on which a correspondingly shaped circuit board can befitted and adhesively secured. In some embodiments of the invention, theheat exchanger 480 may further include additional rearwardly extendingfins 514, 516 that positioned over the legs 506, 508 such that a slot isformed therebetween for securing a circuit board or other components tothe heat exchanger. However, in some embodiments, the fins 514, 516 maybe omitted.

FIG. 6H is a rear isometric view of the heat exchanger 480. As indicatedabove, each of the legs 506, 508 include a lumen 520, 522 into which atube can be fitted and through which cooling liquid or gas can be passedsuch that the liquid or gas flows within the hollow semicircular channelsection of the heat exchanger. In addition, the heat exchanger 480 mayinclude a recess 526 for a thermistor or other temperature-sensingdevice that can transmit signals indicative of the temperature of thedistal tip and signal to a processor in the control unit. Alternatively,the temperature sensor could be located in the body of the distal tip.

FIG. 6I illustrates a semicircular circuit board 550 that is designed tofit within the front face of the heat exchanger 480. Specifically, thecircuit board 550 is adhesively secured in the front face of the heatexchanger 480 against the inner lip 512, as shown in FIG. 6G. Thecircuit board comprises a base material that is thermally conductive,such as a polymer, metal or ceramic or combination thereof, anelectrically isolating dielectric material and a circuit layer. Thecircuit board 550 includes one or more traces 552 and bonding pads 554that are used to deliver electrical current to a pair of LEDs that arelocated on thermally conductive pads 556, 558 that are positioned oneither side of the concave recess 482 in which the lens assembly 470 isfitted when the circuit board is installed in the heat exchanger 480.

In one embodiment of the invention, the base material is copper withconductive pads 556, 558 also made of copper. The LEDs are wire bondedto the bonding pads 554, and trace 552. The rear surface of the circuitboard 550 is preferably coated with a heat conductive, non-reactivebiocompatible material such as gold that is directly exposed to acooling liquid or gas which is pumped through the heat exchanger via thelegs 506, 508.

In one embodiment of the invention, the LEDs 484, 486 are preferablylarge area die, high power, blue light LEDs coated with a phosphormaterial that together produce approximately 60 lumens of light.Although the embodiment shows two LEDs positioned on either side of thelens assembly 470, it will be appreciated that fewer or more LEDs couldbe used and corresponding changes made to the shape of the windows 460,462 positioned in front of the LEDs.

As an alternative, the inside surface of the windows 460, 462 can becoated with a phosphor coating that produces a white light when exposedto the blue light that is produced by the LEDs. The particular phosphoror phosphor combinations selected may depend on the spectralcharacteristics of the LEDs employed. The phosphor or phosphors can bemixed with an epoxy adhesive that is applied to the rear surface of thewindows 460, 462 and cured by exposing the distal tip 450 to anultraviolet light source. Mixing the phosphor coating in an adhesivepromotes a uniform distribution of the phosphor and is easy tomanufacture. Alternatively, the phosphor could be imbibed or directlymixed into the window polymer.

An embodiment of a lens assembly 470 comprises a four-element plasticlens assembly containing several aspheric surfaces to control the imagesharpness and distortion image that provide 140° field of view withnominal f-theta distortion and an f/8 aperture. The individual lensesand aperture of the lens assembly are contained in a plastic cylinderfor insertion into the cylindrically shaped hole of the heat exchanger480. The front surface of the lens assembly is adhesively sealed to thelens port 458 in the cap 450.

As indicated, for colonoscopic applications, a diagonal full-field ofview of 140 degrees with acceptable f-theta distortion is preferable.Image sharpness should be consistent with FDA Guidance Documents forEndoscopes that suggests resolution of 5 line pairs per millimeter on anobject surface, concentric with the entrance pupil, at an objectdistance of approximately 10 mm. This is consistent with the use of aVGA (640×480) pixel color imager such as those manufactured using CMOSor CCD technology by companies such as Micron, Inc. or STMicroelectronics.

The output of the imager chip is preferably of serial digital format toprovide for a reduced wire count to bring the signal from the distal tipto the proximal connector. The cable connecting the proximal end to thedistal tip contains power, ground, clock, differential signal, andcontrol signal lines. Typically, 10-14 wires are required. Byincorporating the serializer into the imager, a highly compact distaltip can be fabricated. Also, the cost of an imager with an integralserializer is less than the cost of a separate imager and serializer andtheir interconnects. Additionally, by removing the clock from the distaltip and locating the clock on the imaging electronics subsystem (60),further reduction of the size of the distal tip is possible withassociated reduction of the cost of the endoscope.

For an imager with a diagonal format size of approximately 4.5 mm, thefocal length of the lens is 1.8 mm in order to cover a full field of 140degrees.

The four element plastic lens assembly 470 is depicted in FIG. 6J, alongwith ray traces from ½ of the field. Elements 570, 572, and 576 areinjection molded from identical plastic such as a crown-like materialTicona Topas. Element 574 is injection molded from polystyrene. Toachieve the required correction, the concave surfaces of elements 570and 572 are rotational aspherics and both convex surfaces of element 576are aspheric. The F/# of the lens is approximately 8, to provide asufficient depth of field. The right most optical element 577 is aprotective coverglass that is incorporated into the imager sensor 490.

In a preferred embodiment of the invention, the image sensor 490comprises a VGA CMOS image sensor with 640×480 active pixels and anon-chip serializer that transmits image data to the control cabinet in aserial form. Such a CMOS image sensor is available as Model No. MI-370from Micron Electronics of Boise, Id. In order to transmit serial imagedata and control signals along the length of the endoscope, the data andcontrol signals are preferably sent digitally using a low voltagedifferential signal (LVDS) protocol along a suitable twisted microcoaxial cable.

To construct the image assembly, the distal cap 450, including flushingport 456 is molded of ABS plastic over the LED windows 460, 462. Thecircuit board 550, having LEDs 482, 484 bonded thereto, is securedwithin the heat exchanger 480 and the CMOS sensor 490 and associatedelectronics 492 are secured to the rear surface 525 of the heatexchanger 480 between the legs 506, 508. The lens assembly 470 isinserted into the concave recess 482 and adjusted longitudinally untilit is at the optimum position to focus light on the image sensor 490before being cemented in place. The completed heat exchanger assemblycan then be inserted into the distal tip 450 and adhesively bonded tocomplete the imaging assembly. The remaining tubes for the low pressurelavage bolus wash channel 454, lens wash and insufflation channel andworking channel are then secured to corresponding lumens in the distaltip in order to complete the distal imaging section of the endoscope.

Variations on the components, dimensions and configuration of thecomponents in the optical assembly are contemplated, which may depend inpart on the desired performance characteristics of the endoscope. Forexample, issues like field of view, levels of illumination, operatingtemperature of the distal tip etc. affect the balance and tradeoff of aparticular configuration. For example, it may be desirable to add afocusing capability to the endoscope by moving the cylindrically shapedlens assembly relative to the image sensor. If the lens assembly can befocused, a lower F# (i.e., faster) lens can be used thereby decreasingthe amount of light required. If less light is required, the need for anactive cooling mechanism to remove any excess heat from the illuminationsource is reduced or eliminated. Alternatively, it may be possible toreplace the water-cooled heat exchanger with a heat pipe that isthermally coupled to the illumination sources or to fill the voids ofthe endoscope with a thermally conductive fluid or other substance.

Because the distance over which the lens assembly must be moved withrespect to the image sensor (or vice versa) is relatively small (e.g., afew hundred microns), a focusing mechanism can be constructed of simplemechanical or electrically activated components such as magnetic,thermally activated bi-metallic components, screw-type advancers, etc.Furthermore, if the lens assembly is contained in a cylindrical recess482 of the type shown in FIG. 6C or an equivalent structure, thefocusing may be simplified because the lens assembly is constrained tobe in-line with the image sensor.

FIG. 7 shows further detail of an embodiment of a distal tip 600 of theendoscope that is similar to that shown in FIG. 6A. In this embodiment,the tip section 600 includes a number of counter bored holes 602 thatare positioned around the outer circumference of the distal tip 600. Thecounter bored holes 602 receive swaged or flanged ends of the controlcables (not shown) that orient the distal tip. Tension on the controlcables pull the distal tip 600 in the direction of the tensioning force.

FIG. 8 is a lengthwise, cross-sectional view of an endoscope 650 inaccordance with one embodiment of the present invention. A distal tip652 is adhesively secured, welded or otherwise bonded within a centerlumen at the distal end of an articulation joint 654. Secured to theproximal end of the articulation joint 654 is a distal end of a shaft656. As discussed above, the shaft 656 is preferably stiffer or ofgreater torsional stiffness or is better able to transmit torque towardsthe distal end of the endoscope than at the proximal end of theendoscope.

The control cables 658 that move the distal tip of the endoscope arepreferably made of a non-stretching material such as stainless steel ora highly oriented polyethylene-terephthalate (PET) thread string. Thecontrol cables 658 may be routed within a center lumen of the shaft 656or, as shown in FIG. 8, may be routed through lumens formed within thewalls of the shaft 656. The control cables 560 extend through guideswithin the walls of articulation joint 654 and terminate either at thedistal end of the articulation joint 654 or in the distal tip section602. In a presently preferred embodiment of the invention, the controlcables are Bowden cables (i.e., a system comprising an outer sheath andan inner cable). For example, the Bowden cable could comprise an outerstainless steel jacket having a lubricous liner such as HDPE and/or aninner cable coated with a lubricant such as silicone in order to reducefriction. Alternatively, the cable may comprise other suitable metals orplastics, and other high modulus materials, such as an incompressibleplastic or metal that may be used for the sheath. The distal end of theouter jacket is received in the proximal end of the articulation joint654 while the proximal end of the jacket is secured in the manualcontroller or the connector that mates the endoscope to the controlcabinet.

If the control cables are routed through the center lumen of the shaft656, the cables are preferably carried in stainless steel or plasticspiral wrapped jackets to prevent binding and a transition guide 670such as that as shown in FIGS. 9A and 9B may be used to guide thecontrol cables into the proximal end of the articulation joint. Thetransition guide 670 has a proximal end 672 that is secured within alumen of the distal end of the shaft. A central body portion 674 of thetransition guide 670 has a diameter equal to the outer diameter of theimaging endoscope. In addition, the body portion 674 includes a numberof diagonal lumens 678 that extend from a center lumen of the proximalend 672 to an outer surface of a stepped distal end 676 of thetransition guide. The distal end 676 is secured within a proximal end ofthe articulation joint 654. Control cables in the diagonally extendinglumens 678 are therefore guided to the outer edge of the catheter wherethey extend through the guides or control cable lumens of thearticulation joint 654.

FIGS. 10A and 10B illustrate one embodiment of a shaft that is used toform an endoscope. The shaft 680 has an extruded sleeve 682 that mayinclude a wire or other braid 684 embedded therein. The braid 684, ifpresent, allows the torque characteristics of the shaft to be adjusted.The sleeve 682 may be formed by placing a sleeve over a mandrel. Thebraid 684 is placed over the sleeve and the mandrel is dipped into orsprayed with a coating material. Preferably the sleeve and coatingmaterial are made of pellethane, polyurethane or other materials ofestablished biomedical use such as polyethylene, polypropylene orpolyvinyl alcohol. In a currently preferred embodiment, the sleeve 682is made of black pellethane with an outside diameter of 0.507 inches andan inside diameter of 0.460 inches. A stainless steel braid is embeddedtherein and has 23 picks per inch. In addition, an inner wrap ofaronatic polyester polyurethane tape completes the outer shaft. Theexterior of the shaft can be coated with a hydrophilic, lubriciouscoating such as the HYDROPASS™ hydrophilic coating available from BostonScientific Corporation, of Natick, Mass., and described in U.S. Pat.Nos. 5,702,754 and 6,048,620, which are herein incorporated byreference.

A plastic spiral wrap 686 such as spiral wire wrap available fromPanduit Inc. is inserted into a center lumen of the shaft 680. Thespiral wrap 686 prevents the shaft 680 from crushing as it is bentaround curves of a patient's anatomy.

In one embodiment of the shaft 680, the spiral wrap has a thickness of0.060 inches and a pitch of {fraction (3/16)} inch. The spiral wrap 686has an outer diameter of 0.500 inches and an inner diameter of 0.380inches and is twisted into the shaft 680 to form an interference fit.However, it will be appreciated that other thicknesses of spiral wrapwith a different pitch could be used to provide the desired columnstrength and bend modulus as well as to prevent kinking.

A metal braid is placed over the articulation joint. The braid hasseveral functions including provides torsional strength to thearticulation joint, keeps the links of the joint aligned duringarticulation and prevents the outer cover from being pinched between thelinks of the joint. The preferred design uses a metal braid butalternatively plastic braids such as PET can be used. The braidproperties (such as braid angle, % coverage, # of pics per inch, etc.)can be adjusted to give the required balance between low articulatingforce and consistent, in-plane articulation. In other embodiments of thedesign, a variable braid may be used over the articulation joint tocontrol the bending arc of the joint. A tighter braid on the proximallinks of the articulation joint encourages the distal links to bendfirst and so the whole joint bends with a smaller bending arc. The outerplastic cover is fitted over the articulation joint portion of the shaftto prevent contaminants from entering the shaft through gaps in thebraided articulation joint.

As indicated above, the proximal section of the endoscope shaft ispreferably more flexible than the distal section. The proximal portionof the shaft is preferably made of a corrugated polyethylene tubing suchas Model No. CLTS 50F-C available from Panduit Inc.

FIG. 11 shows one method of altering the torque fidelity of the distalportion of the shaft. A shaft 700 has a flexible section 702 that istoward the distal end of the endoscope break out box and a stiffersection 704 that is more proximal to the break out box (not shown). Theportion of the endoscope that is more distal has an increasingflexibility toward the distal tip and conversely a higher torquefidelity and column strength proximally. To increase the torque fidelitycharacteristics of the distal section 704 of the shaft, a braid 706 inthat section includes two or more braid or wire strands that are woundin opposite directions. In one embodiment, the wire braid has a pitch of14-16 pics. However, the number of strands and their spacing can beadjusted as needed in order to tailor the torque fidelity of the shaft.

The more distal end 702 of the shaft 700 has a single spiral of wire 706that is preferably wound in the same direction as the plastic spiralwrap in the center lumen of the shaft 700. Again, the torque fidelity ofthe proximal end of the shaft 702 can be varied by adjusting the pitchand/or direction of the wire 706 and its flexibility.

As will be appreciated, the single wire spiral 706 provides some torquefidelity but does have the same torque fidelity as the dual wire braidin the distal section of the shaft in order to allow easy manipulationfor, e.g., resolution of loops. The single wire spiral 706 may beomitted from the distal portion of the shaft if even less torquefidelity is desired.

As discussed above, in order to facilitate steering the distal tip ofimaging endoscope, the endoscope includes an articulation joint thatallows the distal tip to be turned back on itself, i.e., over an arc of180 degrees, by the control cables and can be directed to make that bendin any direction desired about the circumference of the distal tip. Thatis, the operator can select both the amount of the bend or articulationand the direction of the bend. As shown in FIGS. 12A and 12B, anarticulation joint 750 in accordance with one embodiment of theinvention is formed from a cylinder of a plastically deformable materialhaving a central lumen 752, and a number of control cable lumens 754located in the walls of the articulation joint. If desired, the spacebetween the control cable lumens in the cylinder wall may be thinnersuch that the control cable lumens form bosses that extend into thecentral lumen of the cylinder. The control cable lumens 754 arepreferably oriented at 120° apart if three control cables are used or90° apart if four control cables are used.

To facilitate bending of the articulation joint, the cylinder includes anumber of living hinges 760 formed along its length. As can be seen inFIG. 13, each living hinge 760 comprises a pair of opposing V-shapedcuts 770 on either side of the cylinder and are separated by a flexibleweb 772 that forms the bendable portion of the hinge. In the embodimentdesigned for four control cables, each pair of living hinges along thelength of the joint is oriented at 90 degrees with respect to anadjacent hinge.

Upon tensioning of a control cable, those living hinges having webs 772that are in line with the retracting control cable do not bend. Thoseliving hinges having webs that are not in line with the control cablewill be closed, thereby bending the articulation joint in the directionof the control cable under tension.

Another advantage of the articulation joint 750 shown in FIG. 13 is thatthe distal end of the endoscope can be retracted by pulling all thecontrol cables simultaneously. This allows the physician to maneuver thedistal tip in the body, e.g., to “square off” on a lesion, withouthaving to move the remaining length of the endoscope. This may be usefulwhen performing surgical procedures such as obtaining a biopsy orsnaring polyps.

The articulation joint can be formed by extruding a cylinder with thecentral and control cable lumens in place and cutting the cylinder tubewith a knife, laser, milling tool, water jet, or other material removalmechanism to form the living hinges. Alternatively, the articulationjoint can be molded with the living hinge joints in place. As will beappreciated, the angles of the V-shaped cuts that form the hinges may beuniform or may vary along the length of the articulation joint.Similarly, the distance between adjacent living hinges may be uniform ormay vary in order to tailor the bending and torque fidelitycharacteristics of the articulation joint. In one embodiment of theinvention, each living hinge 760 has a closing angle of 30° so that sixhinges are required to provide 180° of movement. The distal end of thearticulation joint 750 may be counter-bored to receive the distal tipsection of the endoscope, as discussed above. Similarly, the proximalend of the articulation joint 750 is adapted to receive the distal endof the shaft section of the endoscope. In the embodiment shown in FIG.13, the control cable lumens 754 are aligned with the widest spacing ofthe live hinges and with the web portion of each hinge. However, it maybe desirable to offset the control cable lumens 754 with respect to thehinges in order to lessen potential binding of the control cables in thehinge. As indicated above, the articulation joint should be made of abiocompatible material accepted for medical use that will bend but willnot collapse. Suitable materials include polyurethane, polyethylene,polypropylene, or other biocompatible polymers.

To prevent wear by the control cables as they are pulled by theactuation mechanism in the control cabinet, it may be desirable toproduce the articulation joint from a material having areas of differentdurometers. As shown in FIGS. 14 and 15, a cylinder formed from anextruded tube 780 has alternating bands of a high durometer material 782and a lower durometer material 784 around its circumference. The lumens786 used to route the control cables are formed in the high durometermaterial 782 to resist abrasion as the control cables are tensioned andreleased and traverse along the lumen. In addition, the high durometermaterial also reduces friction between the control cables and thesurrounding lumen. FIG. 15 illustrates an articulation joint where thecontrol cable lumens are offset with respect to the orientation of theweb portions of the live hinges so that the control cables do not passthrough the web portion 772 of the hinge.

FIGS. 16A and 16B illustrate an alternative embodiment of anarticulation joint. In this embodiment, the joint comprises a series ofball and socket connectors that are linked together. As shown in FIG.16A, each connector includes a socket section 800 and a ball section802. The ball section 802 fits in a socket section 800 of an adjacentconnector. A lumen extends axially through the ball section 802 to allowfor passage of the wires that connect to the light source and the imagesensor and tubes that carry irrigation fluids and insufflation gases.The ball and socket sections are preferably molded of a biocompatiblepolymer.

Each socket section can be formed with a fully formed ball section suchas ball section 810 shown in FIG. 17A. Alternatively, a partial ballsection such as ball section 814 can be formed on a socket section 816as shown in FIG. 17B. To provide room for the control cables to move,the ball section can include slot 818 as shown in FIGS. 17A, 17B thatcuts through the middle and sides of the ball section. Alternatively, anumber of smaller slots 820 can be positioned around the circumferenceof the ball section as shown in FIGS. 17C and 17D. The slots allow thecontrol cables to be shortened under tension. A number of holes 822 atthe interface of the ball section and socket section allows passage ofthe control cables from the socket section into the ball section asshown in FIG. 17D.

In another embodiment of an articulation joint, the articulation jointis made of a series of stacked discs that are positioned adjacent oneanother and move with respect to each other. As shown in FIG. 18A, adisc 850 comprises an annular ring 852 having a pair of rearward facingrocker surfaces or cams 854 and a pair of forward facing rocker surfacesor cams 856. The cams 854 are positioned 180° apart on the rear surfaceof the annular ring 852, while the forward facing cams 856 arepositioned 180 degrees apart on the forward face of the annular ring852. In the embodiment shown, the forward cams 856 are oriented at 90°with respect to the rear cams 854. Opposite each cam on the other sideof the annular ring is a flat land section so that the cams of anadjacent disc may engage with and rock on the flat section. Holes 860are drilled through the annular ring and through the cams for passage ofthe control cables. Upon tension of the control cables, the discs willrock on the surface of the cams 854, 856 thereby bending thearticulation joint in the desired direction.

FIG. 18B shows an articulation joint made up of a series of stackeddiscs 850 a, 850 b, 850 c . . . engaged with one another to form anarticulation joint. A number of control cables 870 a, 870 b, 870 c, 870d, pass through the discs and are used to pull the discs on the camsurfaces to move the joint in the desired direction.

FIGS. 19A and 19B show an alternative embodiment of the articulationjoint shown in FIGS. 18A and 18B. In this embodiment, an articulationjoint comprises a series of stacked discs 880, each comprising anannular ring having a pair of concave pockets 882 on its rear surfaceand a pair of correspondingly shaped convex cams 884 on its frontsurface. The concave pockets 882 are oriented at 90° with respect to theconvex cams 884 so that adjacent discs may be stacked such that the camsof a disc fit within the pockets of the adjacent disc. The correspondingshaped cams 884 and pockets 882 help prevent the discs from rotatingwith respect to one another. Holes or lumens 886 are formed through theannular ring 880 for passage of a number of control cables 890 a, 890 b,890 c, 890 d, as shown in FIG. 19B. The holes or lumens 886 may bepositioned at the center of the cams and pockets. However, the holes forthe control cables may be offset from the position of the cams andpockets, if desired. Preferably discs 880 are molded from abiocompatible polymer having a relatively slick surface, such aspolyurethane, polypropylene, or polyethylene, which reduces frictionbetween adjacent cams and pockets.

FIGS. 20A and 20B show yet another alternative embodiment of anarticulation joint. In this embodiment, the articulation joint is formedof a stack of discs, each of which comprises an annular ring. Theannular ring has forwardly extending cams having an arcuate slot 892molded therein that allows a control cable to move more freely in thecam as the disc is moved relative to an adjacent disc. As best shown inFIG. 20B, the slot 892 tapers from a widest point 894 at the outer edgeof the cam to a narrow point 896 where the slot forms a cylindrical hole898 that extends to the opposite edge of the annular ring 880. A controlwire 896 is free to bend within the widened portion of the arcuate slot892 as an adjacent disc is rotated.

Although the discs of the articulation joints shown in FIGS. 18-20 aregenerally circular in shape, it will be appreciated that other shapescould be used. FIGS. 21A and 21B show an articulation joint formed froma number of sections having a generally square outer shape. As shown inFIG. 21A, a section 900 is a square band having a pair of pins 902 thatextend outwardly on opposite sides of the rear surface of the squaresection. On the opposite sides of the front surface are a pair ofopposing circular recesses 904 that are oriented at 90° to the pins onthe rear surface and are sized to receive the round pins 902 of anadjacent section. In the embodiment shown, the control cables are routedthrough holes or lumens in corner blocks 906 that are found in eachcorner of the square section 900. FIG. 21B shows two adjacent squaresections 900 a, 900 b secured together. As can be seen, the section 900b can rotate up or down on its pins with respect to the adjacent section900 a. Although circular and square articulation sections have beenshown, it will be appreciated that other segment shapes such astriangular or pentagonal, etc., could also be used to form anarticulation joint.

In the embodiments of the articulation joints described above each discor segment that comprises the joint is preferably made of the samematerial. However, it is possible to vary the material from which thesegments are made and/or the physical dimensions or spacing betweenadjacent segments in order to vary the flexibility and torque fidelityof the joint along its length.

In some environments, a full 180° turning radius of the distal tip ofthe imaging endoscope may not be necessary. In those environments, anarticulation joint made of interconnected discs or segments may bereplaced with a flexible member such as a braided stent. FIG. 22 showsan imaging endoscope 925 having a braided stent 930 as the articulationjoint. The braided stent 930 extends between a distal tip 932 and aconnector 934 that joins the proximal end of the stent 930 with thedistal end of a flexible shaft 936. A cover 938 extends over theflexible shaft 936 and the braided stent 930. Control cables (not shown)extend through a lumen of flexible shaft 936 and are used to pull thestent 930 such that the distal tip 932 is oriented in the desireddirection. In addition, pulling all the control cables simultaneouslyallows the distal tip of the endoscope to be retracted.

FIG. 23 shows one method of securing the distal ends of the controlcables to a braided stent 930. The control cables 940 a, 940 b, 940 c,940 d can be woven through the wires of the stent 930 and terminated byforming loops around the wires that comprise the stent. Alternatively,the ends of the cables 940 can be soldered or adhesively secured to thewires of the stent.

FIG. 23A shows yet another alternative embodiment of an articulationjoint 1000 for use with an endoscope of the present invention. Thearticulation joint 1000 is made of a series of stacked rings 1002 a,1002 b, 1002 c, etc. Each ring is preferably formed of a deep-drawnsteel or other metal that allows the ring to be stiff while having athin wall profile in order to maximize the size of the inner lumen.Positioned at equal intervals around the outer circumference of the ringare inwardly extending concave recesses 1004 that receive short springsections 1006 that are used to join adjacent rings together. Two springson opposite sides of a ring 1002 are used to join adjacent ringstogether. For example, if three rings 1002 a, 1002 b, and 1002 c arealigned, the rings 1002 a and 1002 b are joined together with springsegments located at 0° and 180° on the rings, while ring 1002B is joinedto ring 1002C with orthogonally aligned spring segments located at 90°and 270° around the rings. A gap is formed between adjacent rings sothat the pair of springs forms a flexible joint that can bend indirections that are the away from the longitudinal axis of thearticulation joint but has limited ability to compress the articulationjoint in the direction of the longitudinal axis of the articulationjoint. Each spring 1006 is secured within the concave recess 1004 of thering 1002 using an adhesive, crimping, welding, or with other securingmechanism.

The articulation joint 1000 shown in FIG. 23A has the advantage that thecontrol cables pass through the center of the spring segments 1006 andon the outer circumference of the articulation joint, thereby maximizingthe amount of room available for passage of tubes and other cablesthrough the center opening of each ring 1002 and minimizing the torquerequired to bend the articulation joint.

FIG. 23B illustrates an alternative embodiment of the articulation jointshown in FIG. 23A. In this embodiment, the articulation joint comprisesa number of deep drawn or otherwise formed metal rings 1008 a, 1008 b,1008 c that are joined together with springs that are located on theinner circumference of each ring. Each ring is connected to an adjacentring with a pair of spring segments located on opposite sides of thering. The springs 1010 are secured to the inner circumference of therings 1008 with an adhesive or by welding, or using other securingmeans. In the embodiment shown in FIG. 23B, the control cables arerouted through the spring segments and are more closely positioned tothe longitudinal axis of the articulation joint. Being closer to thelongitudinal axis may require more force on a control cable to bend thearticulation joint in a desired direction.

FIG. 23C shows another alternative embodiment of an articulation jointcomprising a series of stacked metal rings 1012 a, 1012 b, 1012 c, etc.Each ring 1012 is joined by a spring 1015 having alternate tightly woundsections 1014 and more loosely wound sections 1016, thereby varying thespring force along the length of the spring. The loosely wound sections1016 allow the articulation joint to collapse in that area while themore closely wound sections 1014 provide the hinge mechanism foradjacent rings 1012. Each of the rings 1012 further includes a stampedpair of inwardly or outwardly extending tabs 1018 through which thesprings are passed thereby forming a surface to which the springs can becrimped, welded, or otherwise secured. In the embodiment shown in FIG.23C, each ring is not completely cylindrical but includes sloped frontand rear surfaces 1020 that extend away from the point at which adjacentrings are joined. The sloped faces of the rings allow increased movementbetween adjacent rings and also provide a stop to prevent adjacent ringsfrom sliding past each other. The sloped surfaces 1020 on adjacent ringsthereby form a V-shaped groove in which the articulation joint is ableto collapse.

FIG. 23D shows another embodiment of an articulation joint that issimilar to the articulation joint shown in FIG. 23B. However, in thisembodiment, the articulation joint is comprised of a number of rings1022 a, 1022 b, 1022 c having oppositely arranged concave recesses 1024and convex recesses that allow a spring 1015 having alternate tightlyand loosely wound segments to pass on the outside of one ring and on theinside of an adjacent ring in an alternating fashion. The oppositelyarranged convex and concave recesses allow a spring to be secured to thering with an adhesive, welding, or other bonding mechanism.

FIGS. 23E and 23F illustrate yet another embodiment of an articulationjoint in accordance with the present invention. In this embodiment thejoint is formed of a series of stacked links 1022 a, 1022 b, 1022 c,etc., that are jointed with alternatingly orthogonally arranged pairs ofspring segments 1024. The link may be formed by rolling and welding flatmetal pieces. The spring segments 1024 are welded, brazed, adhesivelysecured or otherwise bonded to an inner circumference of each ringsegment. The rings and spring segments are preferably made of stainlesssteel or other biocompatible metal. The springs may be secured to therings prior to being cut with a laser or other cutting tool.Alternatively, the springs may be cut into segments and then secured tothe rings with an assembly jig. Springs of varying stiffness may be usedalong the length of the joint to control the bending of the arc of thejoint.

As shown in FIG. 23F, when viewed from the side, each ring has a frontsurface with a flat section 1026 and a pair of sloped sections 1028 thatare sloped rearwardly from the flat surface 1026. The rear surface ofthe ring has a similar shape but the sloped surfaces are oriented at 90°to the sloped surfaces on the front side. Each sloped surface has anangle of 14° from a line perpendicular to the longitudinal axis of thejoint, thereby allowing adjacent rings to bend approximately 28°.

FIG. 23G shows yet another alternative embodiment of an articulationjoint in accordance with the present invention. In this embodiment, thearticulation joint 1030 comprises a series of metal links 1032 a, 1032b, 1032 c, etc., that are formed by deep drawing or stamping steel oranother metal. Each link has a generally ring-like configuration 1034that is either circular or may be many-sided such as octagonal.Furthermore, each link 1032 has a pair of rearwardly extending legs 1036with an outwardly extending tab 1038 at the end thereof. Each of thelegs 1036 is positioned on opposite sides of the link 1032. At 90degrees to the legs 1036, the link 1032 includes corresponding holes1040 in the sidewalls of the link that receive the tabs 1038 from anadjacent segment. Furthermore, the segment 1032 includes integrallyformed wire guides 1042 comprising an eyelet for retaining the controlcable. Adjacent links in the articulation joint are secured together byinserting the tabs 1038 from a first link 1032 into the correspondingholes 1040 of an adjacent link. A braid may be placed over the series oflinks to improve torsional strength without adding to the force requiredto bend the articulation joint. The braid may be incorporated into acover that goes over the articulation joint.

FIG. 23H shows an alternative embodiment of a link like those shown inFIG. 23E. However, in this embodiment, the link 1050 has abutterfly-shaped hole 1052 instead of the round holes 1040 to receivethe tabs of an adjacent link. The butterfly-shaped hole 1052 serves tolimit the extent by which a corresponding flat tab can be rotated froman adjacent link. By adjusting the curvature of the arcs that form thebutterfly-shaped hole 1052, the degree of rotation between adjacentlinks can be controlled. The links 1050 are preferably formed by deepdrawing metal and/or stamping operations.

FIG. 23I illustrates yet another embodiment of an articulation joint ofthe present invention that is formed of a series of interconnected metallinks 1060. Each link 1060 has a pair of rearwardly extending opposinglegs 1062 having inwardly extending tabs at each end. The tabs extendinto corresponding holes or slots of an adjacent link. However, in thisembodiment, the tabs on each of the legs 1062 extend further into thecentral lumen of the articulation joint. Each tab also includes a hole1064 through which a spring 1066 can pass. The holes 1064 thereby lockthe tab in the adjacent link because the spring 1066 prevents the tab1062 from being withdrawn from an adjacent link.

FIG. 23J illustrates yet another embodiment of an articulation joint ofthe present invention that is of a series of interconnected links 1080a, 1080 b, 1080 c, etc. Each link has alternating hoops or eyelets 1082around the circumference thereof that are formed by making a slot thatextends circumferentially around a portion of the link, followed bybending a portion of the link inwardly. The slots are arranged such thata pair of inwardly extending eyelets is formed on opposite sides of afront surface of the link with a pair of eyelets oriented at 90° to theeyelets on the front surface formed on the rear surface of the link.With the eyelets thus formed in the links 1080 a, 1080 b, 1080 c, etc.,the springs can be secured to the links at each of the eyelets.

FIG. 23K shows another embodiment of an articulation joint of thepresent invention that is similar in arrangement to the articulationjoint shown in FIG. 23J. In this embodiment, the articulation jointcomprises a series of metal links 1100 a, 1100 b, 1100 c, etc. Each linkincludes a pair of oppositely formed, inwardly extending tabs 1104 thatare bent in a circle through which an elastomeric tube or spring 1106can be passed. The tubes or springs 1106 are secured in the link bycrimping, welding or otherwise securing the tubes, springs 1106 to thetabs 1104.

FIG. 23L shows yet another alternative embodiment of an articulationjoint in accordance with the present invention. In this embodiment, thearticulation joint comprises a series of stamped or deep drawn metallinks 1120 a, 1120 b, 1120 c, etc. Each link includes a pair offorwardly extending tabs 1022 on its front surface and a pair ofrearwardly extending tabs 1024 on its rear surface. The tabs 1022 and1024 on the front and rear surfaces are oriented at 90 degrees withrespect to each other. Each of the tabs 1022, 1024 includes a holethrough which a securing mechanism can be passed in order to securealigned tabs together. As shown in FIG. 23M, the securing mechanism isprovided by a series of wire springs 1040 a, 1040 b, etc. Each springcomprises a wire with an end that is inserted through the holes of analigned pair of tabs of the articulation joint. The spring 1040 thentravels along the interior lumen of the articulation joint and has asecond end that terminates through the holes of another set of alignedtabs that connect another pair of links. Each spring may further includea loop wound therein that acts as an eyelet for retaining a control wiretherein.

FIGS. 23N-23P illustrate yet another embodiment of an articulation joint1200 for use in a disposable endoscope of the present invention. In thisembodiment, the articulation joint comprises a series of stacked discsof the type shown in FIG. 23N. Each disc 1202 has a front face 1206 anda rear face 1208. Equally spaced around the periphery of the disc are anumber of holes 1210 through which a control cable can pass. The frontface 1206 includes a pair of oppositely arranged flat sections 1207 thatbisects the disc and defines a pair of surfaces that may engage acorresponding flat surface of an adjacent disc. The front face of thediscs further include two sloped sections that are angled proximallyaway from the flat surface 1207. In one embodiment of the invention, thesloped sections are angled at approximately 14° from a lineperpendicular to the longitudinal axis of the disc. Similarly, the rearface 1208 includes two sloped sections that are angled distally awayfrom a pair of flat surfaces that are rotated 90° with respect to theflat surface 1207 on the front face of the disc. As shown in FIG. 23P,the articulation joint 1200 is created by stacking a number of discs1202 a, 1202 b, 1202 c, etc., such that each disc is aligned with anadjacent disc at the flat surfaces, whereby the sloped sections form ahinge that can close under the tension of a control cable passingthrough the articulation joint. In the embodiment shown in FIG. 23P,there are seven pairs of stacked segments 1202, wherein each pair iscapable of producing a 28° bend. Therefore, the articulation joint 1200shown in FIG. 23P can bend a total of 196° in the up, down, left, orright directions. At the proximal end of the articulation joint 1200 isa proximal connector 1220 that joins the articulation joint to thedistal end of the shaft. An outer sheath (not shown) covers the seriesof stacked discs 1202 to prevent each disc from becoming misaligned.

FIG. 23Q shows another disc that is used for the articulation joint ofthe present invention. Each disc 1240 is similar to the discs 1202 shownin FIGS. 23N and 23M. In this embodiment, each segment has a front facewith a pair of sloping surfaces 1242, 1244 that slope away from a pairof opposing flat surfaces 1246. Similarly, on the rear surface of eachsegment, the sloping surfaces are arranged orthogonally to the slopingsurfaces on the front surface. Adjacent discs 1240 a, 1240 b are securedtogether by a pair of oppositely arranged spring segments that havetheir ends set in a recess or a countersink formed in the flat surfaceportion of the disc front and rear surfaces. The spring segments alsoact as guides through which the control cables can pass. Furthermore,the springs prevent adjacent segments from rotating with respect to eachother or otherwise becoming misaligned.

FIG. 23R shows another alternative embodiment of a segment that can beused to form an articulation joint in accordance with the presentinvention. In this embodiment, the articulation joint is comprised of aseries of segments 1300 having a central, cylindrical axle 1302 and anouter cylindrical rim 1304. The axle 1302 is joined to the outercylinder 1304 by a number of outwardly extending spokes 1306. Each spokeis sloped from the center point near the axle downwards towards themidline of the outer ring 1304. The sloped spokes 1306 allow adjacentsegments to touch at the axle points and be rotated with respect to eachother without the spokes hitting each other. Each spoke further includesa lumen 1312 towards the outer edge, through which a control cable canbe passed. The outer rim 1304 of the segment 1300 has alternately spacedteeth 1308, 1310 that are circumferentially arranged such that the teethof one segment align with the recesses of an adjacent segment. Thisdesign ensures that internal tubes do not get entangled duringarticulation.

FIG. 23S shows a series of segments 1300 a, 1300 b, 1300 c, etc.,bending with respect to each other to form an articulation joint. Eachof the individual segments 1300 is preferably molded of a thermoplasticmaterial or metal.

FIG. 23T shows another alternative embodiment of an articulation jointin accordance with the present invention. In this embodiment, thearticulation joint is formed of a series of segments 1330 a, 1330 b,1330 c, etc. Each segment comprises a central pin 1332 and radiallyextending legs 1334 at one end thereof. At the outer edge of each leg1334 is a hole through which a control cable can be passed. The end ofthe central pin fits against a segment like a spinal column therebyallowing each segment 1332 to rock against an adjacent segment. In someembodiments, it may be desirable to cover the segments with a mesh tubeto retain the alignment of the individual segments.

FIG. 23U illustrates another embodiment of a link that is joined toadjacent links to form an articulation joint in accordance with thepresent invention. In this embodiment, the link comprises a metalinjection molded ring having a pair of oppositely arranged, rearwardlyextending rings 1352 and a pair of forwardly extending rings 1354 thatare oriented at 90° with respect to the rearwardly extending rings 1352.Adjacent rings are therefore aligned by placing the forwardly extendingrings of one link against the rearwardly extending rings of an adjacentlink. Each ring 1352 or 1354 includes a hole therein through which arivet can be passed in order to secure the rings together. The innercircumference of the ring 1350 includes a pair of integrated controlcable guides 1356 for restraining movement of a control cable in thelink.

FIG. 23V illustrates an alternative embodiment of a link 1370 that issimilar to the link 1350 shown in FIG. 23T. In this embodiment, eachlink includes a pair of rearwardly extending tabs 1372 having a holetherein and a pair of forwardly extending tabs 1374 that have anintegrally formed pin (not shown) on its inner surface. Once joined, thetabs 1374 having the inwardly extending pins are mated in the holes inthe rearwardly extending tabs 1372 of an adjacent link, therebyeliminating the need to secure adjacent links with a separate rivet. Thelink 1370 also includes a pair of oppositely aligned control cableguides 1376 for restraining movement of a control cable in the link1370.

FIG. 23W shows another alternative embodiment of a link that isassembled with other links to form an articulation joint in accordancewith the present invention. In this embodiment, the link 1390 comprisesan injection molded ring having a pair of oppositely opposed arcuaterecesses 1392 on its rear surface and correspondingly shaped, forwardlyextending arcuate tabs 1394 on its front surface. The tabs 1394 on thefront surface are orthogonally arranged with respect to the arcuaterecesses 1392 on a rear surface. Aligned with the inside surface of eachof the arcuate tabs 1394 is an integrally formed control cable lumen1396 that restrains movement of a control cable in the link 1390.

Because the link 1390 is molded of a thermoplastic material, the arcuatetabs 1394 can be press fit into the arcuate recesses 1392 of an adjacentlink, thereby permitting the adjacent links to rock back and forth withrespect to each other.

In some embodiments, the articulation joint is designed to exert arestoring force so that the endoscope will tend to straighten upon therelease of tension from the control cables. In other cases, it may bedesirable to maintain the position of the distal tip in a certaindirection. In that case, a construction as shown in FIG. 24 can be used.Here, the shaft of the imaging endoscope includes an inner sleeve 1450that is overlaid with two or more plastic spiral wraps 1452, 1454, and1456. Wrap 1452 is wound in the clockwise direction while wrap 1454 iswound in the counter-clockwise direction over the wrap 1452 and the wrap1456 is wound in the same direction as the first wrap 1452. The wrapsare formed of a relatively coarse plastic material such that friction iscreated between the alternatingly wound layers of the wrap. A suitablematerial for the plastic wrap includes a braided polyester orpolyurethane ribbon. Upon tension of the endoscope by any of the controlcables, the plastic spiral wraps will move with respect to each otherand the friction between the overlapping wraps will tend to maintain theorientation of the endoscope in the desired direction. The endoscopewill remain in the desired direction until it is pulled in a differentdirection by the control cables. Covering the alternatingly wound spiralwraps 1452, 1454, and 1456 is a braid 1458. The braid is formed of oneor more plastic, glass fiber or wire threads wound in alternatedirections. An outer sleeve 1460 covers the braid 1458 to complete theshaft.

FIG. 25 shows another alternative embodiment of a shaft construction foruse in an endoscope according to the present invention. The shaftincludes a cover sheath 1470 having bands of a high durometer material1472 and a low durometer material 1474 that alternate around thecircumference of the sheath 1470. The high durometer material and lowdurometer materials form longitudinal strips that extend along thelength of the shaft. Within the sheath 1470 is a plastic spiral wrap1475 that prevents the shaft 1470 from crushing as it is bent in apatient's anatomy. The high durometer materials add to the torquefidelity characteristics of the shaft. The width of the high durometermaterial strips compared to the low durometer material may be adjustedin accordance with the torque fidelity characteristics desired.

During examination with the imaging endoscope, the physician may need totwist the endoscope in order to guide it in the desired direction.Because the outer surface of the endoscope is preferably coated with alubricant and it is round, it can be difficult for the physician tomaintain an adequate purchase on the shaft in order to rotate it. Assuch, the imaging endoscope of the present invention may include agripper mechanism that aids the physician in grasping the shaft foreither rotating it or moving the shaft longitudinally. One embodiment ofa shaft gripping device is shown in FIG. 26. Here, a gripper 1500comprises a U-shaped member having a pair of legs 1502, 1504 that arealigned with the longitudinal axis of an imaging endoscope 20. At thedistal end of the legs 1502, 1504 are two 90° bends 1506, 1508. Thegripper 1500 includes a hole 1505 positioned at the curved, bent portionof the gripper that joins the legs as well as holes in each of the 90°sections 1506, 1508. The imaging endoscope passes through the holes suchthat the gripper 1500 is slideable along the length of the shaft portionof the endoscope. The spring nature of the material used to fashion thegripper causes the legs 1502, 1504 to be biased away from the shaft ofthe endoscope. Only the friction of the opposing holes at the bentportions 1506, 1508 prevent the gripper 1500 from freely sliding alongthe length of the shaft. On the inner surface of the legs 1502, 1504 area pair of touch pads 1510, 1512, having an inner surface that is shapedto match the outer circumference of the shaft portion of the endoscope.When the physician squeezes the legs 1502, 1504 radially inward, thetouch pads 1510, 1512 engage the shaft such that the physician can pushor pull the endoscope or rotate it. Upon release of the legs 1502, 1504,the touch pads 1510, 1512 release from the surface of the shaft and thegripper 1500 can be moved along the length of the shaft to anotherlocation if desired.

FIG. 27 shows a gripper similar to that of FIG. 26 with like parts beingidentified with the same reference numbers. In this embodiment, thegripper includes two hemispherical discs 1520, 1522, positioned on theoutside surface of the legs 1502, 1504. The hemispherical surfaces 1520,1522 are designed to fit within the hand of the physician and increasethe radial distance from the gripper to the shaft such that it is easierto twist the shaft, if desired.

FIG. 28 shows yet another alternative embodiment of a shaft gripper. Inthis example, a gripper 1550 comprises a U-shaped member having a pairof legs 1552, 1554, that are oriented perpendicularly to thelongitudinal axis of the imaging endoscope. The legs 1552, 1554 includea recessed section 1556, 1558 that is shaped to receive the outerdiameter of the shaft portion of the endoscope. A thumbscrew 1560 ispositioned at the distal end of the legs such that the legs can be drawntogether and cause the legs 1554, 1556 to securely engage the shaft ofthe endoscope. Upon release of the thumbscrew 1560, the legs 1554, 1552are biased away from the shaft such that the gripper 1550 can be moved.The shaft can be twisted by rotating the legs 1552, 1554, with respectto the longitudinal axis of the shaft.

FIG. 29 shows an alternative embodiment of the gripper 1550 shown inFIG. 28. In this example, the gripper 1580 includes a U-shaped memberhaving a pair of legs 1582, 1584. At the distal end of each leg is arecess 1586, 1588 that is shaped to receive the outer diameter of theshaft. The shaft is placed in the recesses 1586, 1588, and a thumbscrewis positioned between the ends of the legs 1582, 1584, and the U-shapedbend in the gripper 1580. By tightening the thumbscrew 1590, the legsare compressed against the shaft of the imaging endoscope 20, therebyallowing the physician to rotate the endoscope by moving the gripper1580.

In one embodiment of the invention the endoscope has a movable sleevethat operates to keep the distal end of the endoscope clean prior to useand covers the end of the endoscope that was in contact with a patientafter the endoscope has been used.

FIGS. 30A and 30B illustrate one embodiment of an endoscope 1594 havinga sponge 1504 at its distal end. The sponge fits over the endoscope andhas a peel off wrapper that may be removed and water or other liquid canbe applied to the sponge. The water activates a hydrophilic coating sothat the distal end of the endoscope has an increased lubricity. Inaddition, the sponge functions as a gripper when compressed allowing thephysician to pull and/or twist the endoscope.

A collapsible sleeve 1598 is positioned over the distal end of theendoscope and can be retracted to expose the lubricated distal tip ofthe probe. In one embodiment, the sleeve 1598 is secured at its distalend to the sponge 1594 and at its proximal end to the breakout box.Moving the sponge proximally retracts the sleeve so that the endoscopeis ready for use. After a procedure, the sponge 1594 is moved distallyto extend the sleeve over the distal end of the endoscope. With thesleeve extended, any contaminants on the probe are less likely tocontact the patient, the physician or staff performing the procedure.

In some instances, it may be desirable to limit the amount of heat thatis dissipated at the distal end of the imaging endoscope. If lightemitting diodes are used, they generate heat in the process of producinglight for illumination. Similarly, the image sensor generates some heatduring operation. In order to limit how hot the distal end of theendoscope may become and/or to provide for increased life for thesecomponents, it is necessary to dissipate the heat. One technique fordoing so is to fashion a passive heat sink at the distal tip of theimaging endoscope. As shown in FIG. 31, a distal tip 1600 includes a cap1602 and a heat dissipating section 1604 that is made of a heatdissipating material such as a biocompatible metal. The heat dissipatingsection 1604 includes a semicircular opening 1606 having a relativelyflat base 1608 that extends approximately along the diameter of the heatdissipating section 1604. The flat base 1608 forms a pad upon whichelectrical components such as the LEDs and image sensor can be mountedwith a thermally conductive adhesive or other thermally conductivematerial. The heat generating devices will transfer heat generatedduring operation to the heat dissipating section 1604. The distal cover1602 covers the distal end of the heat dissipating section 1604 in orderto prevent the heat dissipating section 1604 from touching the tissue inthe body as well as to protect the body as the imaging catheter is movedin the patient. Prisms, lenses, or other light bending devices may beneeded to bend light entering the distal end of the endoscope to anyimaging electronics that are secured to the relatively flat base 1608 ofthe heat dissipating section 1604.

FIG. 32 shows a heat dissipating distal tip of an endoscope wherein thedistal tip does not include a cover but is molded from a single piece ofheat dissipating material such as a biocompatible metal. The heatdissipating section 1620 again includes a semicircular opening with arelatively flat surface 1622 that extends along the diameter of thesection and on which heat generating electronic devices can be mounted.With a semicircular opening formed in the distal end of the heatdissipating distal tip 1620, the illumination mechanism and image sensorare mounted on the flat surface 1622. The irrigation port is oriented todirect water over the hemispherical cutout in order to clean theillumination mechanism and image sensor or image sensor lenses.

In yet another embodiment of the invention, the imaging devices at thedistal end of the endoscope can be cooled by air or water passed througha lumen to the end of the endoscope and vented outside the body. Forexample, air under pressure may be vented through an orifice near theimaging electronics. The expansion of the air lowers its temperaturewhere it cools the imaging electronics. The warmed air is then forced tothe proximal end of the endoscope through an exhaust lumen.Alternatively, the endoscope may include a water delivery lumen thatdelivers water to a heat exchanger at the distal tip. Water warmed bythe electronic components in the distal tip is removed in a water returnlumen. Air or water can be alternatively be released directly to thepatient lumen if the volumes and temperatures are physiologicallyacceptable.

FIG. 33 shows an alternative embodiment of the passive heat dissipatingdistal tip shown in FIG. 31. In this example, the heat dissipatingdistal tip 1640 has a number of scalloped channels 1642 positionedaround the circumference of the distal tip. The scalloped channels 1642increase the surface area of the heat dissipating distal tip, therebyfurther increasing the ability of the tip to dissipate heat from theillumination and imaging electronic devices.

Although the present endoscope system has many uses, it is particularlysuited for performing colonoscopic examinations. In one embodiment, a10-13 mm diameter prototype having a 0.060 inner spiral wrap with apitch of {fraction (1/4)} inch and coated with a hydrophilic coating wasfound to have a coefficient of friction of 0.15 compared to 0.85 forconventional endoscopes. In addition, the endoscope of the presentinvention required 0.5 lbs. of force to push it through a 2-inchU-shaped bend where a conventional endoscope could not pass through sucha tight bend. Therefore, the present invention allows colonoscopes to bemade inexpensively and lightweight so that they are more comfortable forthe patient due to their lower coefficient of friction and bettertrackability.

In addition to performing colonoscopies, the endoscope system of thepresent invention is also useful with a variety of surgical devicesincluding: cannulas, guide wires, sphincterotomes, stone retrievalballoons, retrieval baskets, dilatation balloons, stents, cytologybrushes, ligation devices, electrohemostasis devices, sclerotherapyneedles, snares and biopsy forceps.

Cannulas are used with the endoscope system to cannulate the sphincterof Oddi or papilla to gain access to the bile or pancreatic ducts. Guidewires can be delivered down the working channel of the endoscope andused as a rail to deliver a surgical device to an area of interest.Sphincterotomes are used to open the papilla in order to place a stentor remove a stone from a patient. Stone retrieval balloons are usedalong with a guide wire to pull a stone out of a bile duct. Retrievalbaskets are also used to remove stones from a bile duct or other tract.Dilatation balloons are used to open up strictures in thegastrointestinal, urinary or pulmonary tracts. Stents are used to openup strictures in the GI, urinary or pulmonary tracts. Stents can bemetal or plastic, self-expanding or mechanically expanded, and arenormally delivered from the distal end of a catheter. Cytology brushesare used at the end of guide wires to collect cell samples. Ligationdevices are used to ligate varices in the esophagus. Band ligatorsemploy elastic bands to cinch varices. Electrohemostasis devices useelectrical current to cauterize bleeding tissue in the GI tract.Sclerotherapy needles are used to inject coagulating or sealingsolutions into varices. Snares are used to remove polyps from the GItract, and biopsy forceps are used to collect tissue samples.

Examples of specific surgical procedures that can be treated with theendoscopie system of the present invention include the treatment ofgastroesophageal reflux disease (GERD) by the implantation of bulkingagents, implants, fundoplication, tissue scarring, suturing, orreplacement of valves or other techniques to aid in closure of the loweresophageal sphincter (LES).

Another example of a surgical procedure is the treatment of morbidobesity by deploying implants or performing reduction surgery, gastricbypass and plication or creating tissue folds to help patients loseweight.

Endoscopic mucosal resection (EMR) involves the removal of sessilepolyps or flat lesions by filling them with saline or the like to liftthem prior to resection. The endoscope of the present invention can beused to deliver needles, snares and biopsy forceps useful in performingthis procedure.

In addition, the video endoscope system of the present invention can beused to perform full-thickness resection (FTRD) in which a portion of aGI tract wall is excised and the wounds healed with staplers orfasteners. Finally, the endoscope system of the present invention can beused to deliver sclerosing agents to kill tissues or drug deliveryagents to treat maladies of internal body tissues.

While the preferred embodiment of the invention has been illustrated anddescribed, it will be appreciated that various changes can be madetherein without departing from the scope of the invention. For example,although some of the disclosed embodiments use the pull wires tocompress the length of the endoscope, it will be appreciated that othermechanisms such as dedicated wires could be used. Alternatively, aspring can be used to bias the endoscope distally and wires used tocompress the spring thereby shortening the length of the endoscope.Furthermore, although the disclosed embodiments use rotary servo motorsto drive the control cables, other actuators such as linear actuatorscould be used. Similarly, although the endoscope discussed in connectionwith the preferred embodiment includes a working channel, it will beappreciated that such a channel may be omitted and the resultingcatheter used to deliver a special purpose tool such as a snare, RFablation tip, etc., to a desired location. Alternatively, the cathetercould be used solely for imaging. Finally, although the disclosedcomponents are described as being used in a video endoscope, it will beappreciated that many components may have separate utility by themselvesor in other medical devices. Therefore, the scope of the invention is tobe determined from the following claims and equivalents thereof.

1. An endoscopic system, comprising: a housing including one or moreactuators that selectively move the distal tip of an endoscope in atleast one desired direction; an endoscope having a distal end that isinserted into the body of a patient and a proximal end that is removablycoupled to the housing; a directional controller for directing the oneor more actuators in the housing to move the distal tip of the endoscopein the desired direction; means for determining a force required to movethe distal tip of the endoscope; and a feedback mechanism coupled to thedirectional controller for providing feedback to a user of the forcerequired to move the distal tip of the endoscope.
 2. The endoscopicsystem of claim 1, wherein the directional controller is a joystick andthe feedback mechanism selectively adjusts the tension of a spring onthe joystick.
 3. The endoscopic system of claim 1, wherein thedirectional controller is a joystick that is movable with at least twomotors and the feedback mechanism selectively adjusts the torque of thetwo motors.
 4. The endoscopic system of claim 1, wherein the actuatorsselectively move the distal end of the endoscope in a plurality ofdirections and the force determining means comprises a processor in thehousing that estimates the force required to move the distal tip,wherein the force is supplied to the feedback mechanism, and wherein thefeedback is a tactile signal that is proportional to the force requiredto move the distal end.
 5. The endoscopic system of claim 1, wherein theactuators are motors that selectively tension control cables within theendoscope and the means for determining the force required to move thedistal tip of the endoscope includes a position sensor and a torquesensor on the motors.
 6. The endoscopic system of claim 1, wherein thehousing includes a processor that separates a force required to move aproximal portion of the endoscope from the force required to move thedistal tip, and wherein the feedback is tactile feedback provided to theuser that is proportional to the force required to move the distal tip.7. The endoscopic system of claim 1, wherein the housing is a controlunit including the one or more actuators and the force determiningmeans, the actuators selectively moves the distal end in a plurality ofdirections and the force determining means estimates a force to move aproximal portion of the endoscope and a force to move a distal tip ofthe endoscope, wherein the force to move the distal tip is supplied tothe feedback mechanism and the feedback is a tactile signal that isproportional to the force required to move the distal tip.
 8. A systemfor providing feedback to a user of an endoscope, comprising: anendoscope having a distal end that is inserted into a patient and aproximal end that is connectable to a housing; control cables in theendoscope that are selectively tensioned by actuators in the housing tosteer the distal end; sensors on the actuators that determine a forcerequired to tension the control cables; a processor that directs theactuators to tension the control cables, and determines an extra forceabove the force to steer the distal end in a particular direction; and afeedback mechanism that provides an indication to a user of the extraforce.